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The United States-Mexican War, 1846-1848

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  • Mexico’s troubles
  • U.S. annexation of Texas
  • Polk’s expansionist strategy
  • Onset of war
  • Underlying causes: race, history, and “Manifest Destiny”

III. Costs and conduct of the war

  • Military campaigns and occupations
  • General Taylor and the occupation of northeastern Mexico
  • The “Army of the West” in Nuevo México and Alta California
  • General Scott and the occupation of middle Mexico

IV. Debate and opposition to the war within the United States

  • Historical interpretations and perspectives

Endnotes and Image credits

Did you know?

  1. The war officially began over a border dispute in what is now south Texas, but President James K. Polk had a larger goal in mind – the acquisition of Mexico’s northern territories of Alta California and Nuevo México.
  2. President Polk initially planned a limited war, but Mexico’s stubborn refusal to part with its northern territories led to a decision to invade and conquer Mexico City.
  3. Mexico lost 55% of its territory to the United States between 1836 and 1848.
  4. The U.S. Army won every major battle in the war, but it was unable to suppress guerrilla activity, which never ceased.  This was the first U.S. counterinsurgency war in a foreign country.
  5. Mexicans civilians suffered from the U.S. occupation, whether from personal violence, extended anti-guerrilla operations, bombardment of cities, or the imposition of martial law.  U.S. military forces remained in Mexico from May 1846 until July 1848.
  6. Of the 90,000 U.S. soldiers who served in Mexico, nearly 14,000 died, a death rate of 15.5% – the highest rate of any foreign war in U.S. history.
  7. Regarding the causes of death, one U.S. soldier in seven died in battle or from battle wounds; six in seven died from disease, accidents, or other causes.
  8. Among those who believed that the war was unnecessary and/or unjust were former president John Quincy Adams, future presidents Abraham Lincoln and Ulysses S. Grant, former vice-president John C. Calhoun, and three-time presidential candidate Henry Clay.
  9. In April 1847, the Massachusetts legislature passed a resolution denouncing the war as “a gigantic crime” waged against a “weak neighbor” for the purposes of conquest, territorial aggrandizement, and the extension of slavery.
  10. On January 3, 1848, the House of Representatives passed a resolution stating that “the war was unnecessarily and unconstitutionally commenced by the president.”
  11. In contrast to the antiwar movement, the All of Mexico movement that arose in 1847 wanted to annex all of Mexico to the United States.  President Polk was inclined to seek more territory but not all of Mexico.
  12. The U.S. agent who negotiated the peace treaty, Nicholas Trist, had been recalled by the president, but he negotiated the treaty anyway.  The president reluctantly accepted the treaty.

I. Introduction

The United States and Mexico went to war in May 1846.  Except for the first battles fought in a disputed border area, all of the fighting took place in Mexico.  The United States invaded and occupied Mexico City.  The war took the lives of at least 25,000 Mexicans and nearly 14,000 U.S. soldiers.  The United States finally withdrew its forces in July 1848, after the Treaty of Guadalupe Hidalgo was signed and ratified by both countries.  Mexico reluctantly ceded 530,000 square miles of territory to the United States and gave up claims to disputed territory in Texas.
Mexicans then and now have viewed this war as unnecessary and unjust.  In a ceremony in 2010 commemorating those who had sacrificed their lives in defense of their nation, Mexican President Felipe Calderon described the war as an “unjust military aggression motivated by clearly imperialistic interests.”  In the United States, views on the war have been more contested, but a significant proportion of American leaders, citizens, and historians, past and present, have viewed it as unnecessary and unjust.  In the words of one historian, “It was a war of choice, not of necessity, a war of aggression that expanded the size of the United States by nearly one quarter and reduced that of Mexico by half.”[1]
President James K. Polk

President James K. Polk

Throughout the war, as U.S. forces invaded and occupied northern Mexico then captured Mexico City, President James K. Polk maintained that the United States was fighting “a just war.”  In his war message to Congress on May 11, 1846, he charged that Mexican forces had “invaded our territory and shed the blood of our fellow-citizens on our own soil.”  Given the “grievous wrongs perpetrated by Mexico,” said Polk, the United States had no choice but to fight for the “vindication of our rights and defense of our territory.”[2]  Many prominent Americans at the time disagreed with the president.  Among them were former president John Quincy Adams, future presidents Abraham Lincoln and Ulysses S. Grant, former vice-president John C. Calhoun, and three-time presidential candidate Henry Clay.

Illinois Representative Abraham Lincoln

Illinois Representative Abraham Lincoln

Two weeks after the president presented his war message, John Quincy Adams delivered a speech in the House of Representatives in which he denounced “this most outrageous war,” charging that its real purpose was territorial aggrandizement and the expansion of slavery.  Illinois congressman Abraham Lincoln, in his first major speech in the House on January 12, 1848, challenged the president’s claim that American blood had been shed on American soil, stating that the evidence fell “far short of proving his justification.”  In his lawyerly fashion, Lincoln presented counter evidence showing that Mexico had a better claim to the disputed territory.  The president himself, Lincoln added whimsically, was a “bewildered, confounded, and miserably perplexed man.”[3]

Lieutenant Ulysses S. Grant

Lieutenant Ulysses S. Grant was 24 years old when the war broke out.  Leaving his fiancé in Ohio, he served under generals Zachary Taylor and Winfield Scott, participating in major battles in northern and central Mexico.  Grant found no glory in war but rather mourned its waste and loss of life.  Reflecting on his war experiences later in life, he told a journalist, “I do not think there was ever a more wicked war than that waged by the United States on Mexico.”  He reiterated this judgment in his memoirs, describing the war “as one of the most unjust ever waged by a stronger against a weaker nation.  It was an instance of a republic following the bad example of European monarchies, in not considering justice in their desire to acquire additional territory.”[4]

Senator John C. Calhoun of South Carolina was a Democrat and a slaveholder, like the president, but he, too, could not endorse the war.  In Calhoun’s view, President Polk had usurped the constitutional powers of Congress by placing U.S. troops in the disputed territory and provoking hostilities.  As he explained in a speech on January 4, 1848, “I opposed the war then [at the outset] not only because I considered it unnecessary, and that it might have been easily avoided; not only because I thought the President had no authority to order a portion of the territory in dispute and in possession of the Mexicans to be occupied by our troops . . . but from high considerations of reason and policy, because I believed it would lead to great and serious evils to the country, and greatly endanger its free institutions.[5]

Whig Party leader Henry Clay

Henry Clay, leader of the Whig Party, was no longer the “war hawk” of 1812.  He had honed his diplomatic skills as secretary of state under President John Quincy Adams and facilitated domestic political compromises as well.  He believed that a compromise with Mexico could have been achieved had Polk negotiated “in a true spirit of amity and conciliation.”  Speaking to a large gathering in Lexington, Kentucky on November 13, 1847, the elder statesman argued that the president had rejected this “pacific and moderate course” in favor of planting U.S. forces “in a warlike attitude” in the disputed territory.  “This is no war of defense,” he declared, “but one unnecessary and of offensive aggression. It is Mexico that is defending her fire-sides, her castles and her altars, not we.”

The war was personally tragic for Clay, as his son, Henry Clay Jr., was killed in the Battle of Buena Vista in February 1847.  Informed that his son had died fighting bravely, the grieving father confided to a friend, “That consolation would be greater if I did not believe that this Mexican War was unnecessary and of an aggressive character.”  His son, he said, had not inquired as to “the causes of the War.  It was sufficient for him that it existed in fact, and that he thought the Nation was entitled to his services.”[6]

II.  Origins of the U.S.-Mexican War

The origins of the U.S.-Mexican War fall into two categories.  One derives from a dispute over the border of Texas.  The other, from the Polk administration’s desire to acquire Mexico’s northern territories of Alta California and Nuevo México.  President Polk did not want war per se.  He initially hoped that Mexico would agree to American border claims and sell the desired territories to the United States.  When Mexico refused, Polk provoked a war and took possession of the territories.  According to the diplomatic historian George C. Herring:

Polk and many of his countrymen were determined to have Texas to the Rio Grande and all of California on their own terms. . . . Polk appears not to have set out to provoke Mexico into what could be used as a war of conquest.  Rather, contemptuous of his presumably inferior adversaries, he assumed he could bully them into giving him what he wanted. . . . Certain that an inferior people would be no match for Americans, he envisioned a war of three to four months.  The United States would secure control of Mexico’s northern provinces and use them to force acceptance of the Rio Grande boundary and cession of California and New Mexico.[7]

Mexico’s troubles

Antonio López de Santa Anna

Antonio López de Santa Anna

Mexico achieved independence from Spain on August 24, 1821.  The eleven-year war that led to independence cost the lives of over half a million Mexicans, including one out of every ten fighting-age men.  About half the population of six million were indigenous peoples of various ethnicities, 30 to 40 percent were mestizos (a mixture of Spanish and Native American), and 10 to 20 percent were of Spanish extraction (mostly criollos, born in Mexico).  The country remained impoverished and politically unstable for decades after independence.  According to the Mexican Embassy, “During the next 30 years, Mexico had close to 50 governments, almost all as the result of military coups.  Eleven of them were presided by one man, General Antonio López de Santa Anna.”[8]  In 1824, Mexico adopted a constitution modeled in part on that of the United States, except Indians were deemed citizens with rights to vote and hold public office.  Mexico effectively banned slavery through a series of laws in the 1820s, which in turn led to an infiltration of runaway slaves from the United States.  By 1840, there were an estimated 6,000 Blacks in the country.  A population census in 1842 indicated a total Mexican population of just over seven million, as compared to about eighteen million in the United States.

Indigenous territories within Mexico, 1830s

Indigenous territories within Mexico, 1830s

The vast stretches of land in the north inherited by Mexico from Spain were home to Comanches, Apaches, Kiowas, Navaho, Hois, Tenewas, Yamparikas, Pueblos, and other tribes.  Mexico’s claim to the region did not negate the right of these indigenous groups to occupy their lands.  Rather, the claim was meant to preclude colonization and exploitation by other European and EuroAmerican powers.  Most of the indigenous peoples in the northern region were hostile to Spanish and Mexican incursions, although not necessarily to trade.  The Mexicans labeled the hostile tribes indios bárbaros (barbarians), in contrast to the peaceful tribes that integrated into the Mexican system, such as the Pueblos.

Raids by hostile tribes became more frequent in the 1830s and 1840s, in large part because the Mexican government could not afford to protect its northern provinces.  Governors of the northern provinces issued desperate appeals to the central government, but to no avail.  According to the historian Brian DeLay, native warriors “killed or captured several thousand northern Mexicans between 1831 and 1846.”  They also plundered homes and stole valuable horses and livestock, effectively crippling the ranching and farming economies in the north.  Mexican leaders attempted to pacify the Indians with an ambivalent mix of trade incentives, peace agreements, and revenge attacks.  The revenge attacks, which included displaying “Comanche scalps, ears, hands, and heads in Mexican settlements as trophies,” increased the cycle of violence.[9]
Mexico was also troubled by foreign powers.  In 1829, Spain attempted to re-conquer Mexico, attacking the port of Tampico with a force of 3,600 men.  A Mexican army led by Antonio López de Santa Anna drove them off, after which Santa Anna became known as the “Hero of Tampico.”   In 1838, the French navy blockaded, bombarded, and invaded the port of Veracruz, the object being to obtain financial compensation for the property losses of French citizens during various upheavals in Mexico.  Santa Anna once again came to the rescue, winning a battle and losing his leg – which was buried with full military honors.  The French navy nonetheless continued its blockade and Mexico was forced to pay the French 600,000 pesos.  Similar claims against the Mexican government for property losses were made by the British and American governments acting on behalf of their citizens.  The British government did not attempt to collect the debt, recognizing the impoverished state of the Mexican government, but the U.S. continued to hound Mexico.  In February 1841 a joint U.S.-Mexican commission set a figure of $2 million to be awarded to U.S. citizens.  The Mexican government made three payments then ran out of money.  In 1846, President James K. Polk cited the unpaid balance as one reason to go to war against Mexico; and in 1847, he cited it as reason for Mexico to cede its northern provinces to the United States.
Mexican states and territories (click to enlarge)

Mexican states and territories (click to enlarge)

Mexico’s political instability grew worse in the 1830s.  Santa Anna won the presidential election of 1833, but soon switched his allegiance from the liberals to the conservatives and established a caudillo (strongman) state.  The Mexican Congress was dismissed and a new constitution was written in 1836 that centralized power in the federal government.  (The constitution of 1824 had distributed governmental powers among nineteen semiautonomous states and five territories.)  Santa Anna’s authoritarian moves sparked widespread protests and outright rebellion in the states of Coahuila y Tejas, Nuevo León, San Luis Potosí, Sonora, Tamaulipas, Yucatán, Zacatecas, and in the territories of Nuevo México and Alta California.  Tejas separated from Coahuila to form its own Republic of Texas.  General Santa Anna raised an army and defeated a large rebel force in Zacatecas in May 1835, but he was unable to suppress the rebellion in Texas.

In 1835, Texas was home to 30,000 Anglo immigrants and 8,000 Mexican Tejanos.  The first Americans to settle in eastern Texas did so legally through an empressario land grant from the Spanish government in 1820, later honored by the Mexican government.  Under the guidance of Stephen Austin, Anglo American immigrants obtained large parcels of land for a small price.  They were supposed to become Mexican citizens and convert to Catholicism but very few did.  A separatist Anglo rebellion erupted in late 1826 (the Fredonian Rebellion) but Austin and most other Anglos chose to aid the Mexican government in suppressing it.  Fearing more such rebellions, Mexico passed a law in April 1830 that severely restricted further American immigration.  Americans nonetheless kept coming – illegally.  Many of these illegal immigrants, moreover, brought their black slaves with them, violating another Mexican law.  To get around the letter of the law, they declared that their slaves were indentured servants.  The Texan quest for independence, as such, was motivated by both a desire to be free from Mexican rule and a desire to establish and expand slavery in a land where it had been forbidden.
The Alamo mission near San Antonio

The Alamo mission near San Antonio

The Texan fight for independence began in October 1835 and lasted seven months.  The rebel force consisted of Texas Rangers, with much experience fighting Indians, and American volunteers streaming into Texas, including the famous Tennessee congressman David Crocket.  All of the latter acted in violation of the U.S. Neutrality Act of 1818, which forbade private military expeditions, but President Andrew Jackson ignored the law.  The Texan rebels were defeated at the old Alamo mission near San Antonio on March 6, 1836, and again at Goliad on March 22, but rallied to defeat Santa Anna’s army at the Battle of San Jacinto on April 21.  The Mexican Army executed 342 prisoners-of-war at Goliad.  Texans responded in kind at San Jacinto, “slaughtering hundreds of unresisting Mexican soldiers,” according to the historian William Weeks, although the deaths were officially reported as battle deaths (the tally was 650 Mexicans and 11 Texans killed).[10]

3_Texas_mapofthetexasrevolutionSanta Anna himself was captured and forced to sign the Velasco “treaties” under threat of death.  These “treaties” recognized Texas independence and pushed the border of Texas to the Rio Grande.  The Mexican Congress refused to ratify the “treaties,” but Texans nonetheless held them as valid, including the preposterous border claim  that extended far to the south and west of American settlements.  The traditional border of Tejas, established by Spanish imperial authority in 1816, was the Nueces River, 150 miles to the north of the Rio Grande.  Virtually no Americans resided in the land between the Nueces River and Rio Grande.  The Mexican government, for its part, refused to accept Texas independence.  As Mexican scholar Jesús Velasco-Márquez writes, “Mexico’s position was very similar to that adopted by the U.S. government when it faced the problem of the secession of its southern states years later. . . . From Mexico’s point of view, the annexation of Texas to the United States was inadmissible for both legal and security reasons.”[11] 
Texas and Mexico officially remained at war for most of the nine years that Texas existed as an independent republic.  Rebels in the Mexican states of Coahuila, Tamaulipas, and Nuevo León found refuge in the independent Republic of Texas; and some Anglo Texans fought with the Mexican rebels, although “they often amounted to less than 10 percent of the total federalist [rebel] force,” according to DeLay.  Texans furthermore raided towns and homesteads along the Rio Grande, prompting Mexican officers to label them “bandits and pirates.”[12]  Texas thus constituted a serious security threat to Mexico.  In June 1841, Texas President Mirabeau B. Lamar sent a combined military and trade expedition of 320 men to Nuevo México in an attempt to persuade or intimidate the territory’s leaders into joining the Republic of Texas.  The Texans expected to be welcomed but instead were taken prisoner by Mexican forces (and released a year later).  In September 1842, the Mexican government took the offensive and sent a force of 1,600 soldiers to briefly occupy San Antonio, located on the north side of the Nueces River.  In December, some 260 Texans crossed the Rio Grande and attempted to take over the town of Mier, 180 miles upriver of Matamoros.  Their efforts were thwarted by Mexican troops and most of the Americans were taken prisoner.  Weary of fighting, and with encouragement from Great Britain, Texas President Sam Houston agreed to an armistice with Mexico in June 1843.

U.S. annexation of Texas

In Washington, President Martin Van Buren (1837-1841) remained officially neutral during the low-level war between Texas and Mexico.  Like his predecessor, Andrew Jackson, Van Buren rejected requests to annex Texas for a number of reasons.  First, northern free states and especially abolitionists were opposed to it, evident in the fact that eight state legislatures passed resolutions and 600,000 citizens signed petitions against annexation.  Secondly, the annexation of Texas could very well involve the U.S. in a war with Mexico, as Texas was still part of Mexican territory in the eyes of the Mexican government.  Thirdly, annexation would surely involve the U.S. in the ongoing Indian wars in the region; and, fourthly, related to this, the U.S. Army had its hands full fighting Seminoles in Florida.  Americans had expected a quick victory in Florida, but Seminole leader Osceola proved to be an elusive foe.  The Second Seminole War lasted seven years, from 1835 to 1842, the longest in U.S. history up to that time, and cost the lives of some 1,600 U.S. troops and $40 million.   It was one of the most unjust wars in U.S. history, being fought for the sole purpose of banishing Seminoles to reservations in the west and making room for white Americans and their slaves in Florida.

Henry Clay & Theodore Frelinghuysen poster

James K. Polk & George Dallas poster, 1844

President John Tyler (1841-1845) was more amenable to annexation than his predecessor.  Tyler signed a treaty of annexation with Texas in April 1844, but the Senate refused to ratify it, thus leaving the issue hanging as the presidential election approached that fall.  Van Buren was expected to be the Democratic Party nominee, but his opposition to the annexation of Texas led expansionists to push for the relatively unknown James K. Polk.  Polk was a former Tennessee congressman, Speaker of the House (1835-39), and one-term governor, but he had lost the last two gubernatorial elections.  With Andrew Jackson’s support, however, and a few rule manipulations, Polk became the nominee over front runner Van Buren.

Polk ran on an expansionist platform designed to appeal to both southerners and northerners, respectively calling the “re-annexation” of Texas and the “re-occupation” of Oregon territory – misleading terms that implied existing American ownership.  Polk did not mention California or New Mexico while on the campaign trail.  Whig presidential candidate Henry Clay opposed the annexation of Texas without first settling the border dispute with Mexico.  He voiced his opinion in a letter to the National Intelligencer on April 17, 1844:

I certainly am not willing to involve this country in a foreign war for the object of acquiring Texas. I know there are those who regard such a war with indifference, and as a trifling affair, on account of the weakness of Mexico, and her inability to inflict serious injury upon this country.  But I do not look upon it thus lightly. I regard all wars as great calamities, to be avoided, if possible, and honorable peace as the wisest and truest policy of this country. . . . Honor and good faith and justice are equally due from this country towards the weak as towards the strong . . . I consider the annexation of Texas, at this time, without the assent of Mexico, as a measure compromising the national character, involving us certainly in war with Mexico, probably with other foreign powers, dangerous to the integrity of the Union, inexpedient in the present financial condition of the country, and not called for by any general expression of public opinion.[13]

Clay was expected to win the presidential election in November 1844, but Polk pulled an upset.  Polk won a small plurality of the popular vote, 49.5%, as compared to Clay’s 48.1%, with Liberty Party candidate James G. Birney garnering 2.3%, including 15,800 votes in the state of New York.  According to the historian Brian DeLay, “Had Clay won just 5,107 more votes in New York State from the nearly one million cast, he would have become president and there almost certainly would have been no annexation of Texas, no war with Mexico, no U.S. Civil War, and a vastly different continental story.  But by the narrowest of margins Polk’s vision took the day.”[14]  Polk’s electoral victory led to a new surge of expansionist fervor in the country.  Sensing the time was right, outgoing President Tyler proposed to Congress that Texas be admitted as a state rather than a territory, thereby requiring majority approval in both houses of Congress rather than two-thirds of the Senate (the last attempt had failed).  The strategy worked and Tyler signed an annexation bill on March 1, 1845, three days before Polk was inaugurated.

General José Joaquín de Herrera

Mexico’s response to the annexation measure was to sever diplomatic relations with the United States.  Mexican president José Joaquin de Herrera issued a proclamation on June 4, 1845, declaring that “annexation of Texas to the United States . . . attacks all the rights that Mexico has to that territory, is an insult to her dignity as a sovereign nation, and threatens her independence and political existence.”  The proclamation decreed, “The Mexican nation calls upon all her children to the defense of her national independence.”  This proclamation has sometimes been interpreted as a declaration of war against the U.S., but it was not.  It was a call to arms in defense of the nation.[15]  Herrera came to power in late 1844, replacing Santa Anna.  At the time, he issued a manifesto declaring that Santa Anna had failed to prosecute the war against Texas.  The U.S. annexation of Texas, however, dramatically changed the situation. 

Herrara knew it would be foolhardy to wage a war against the United States and thus he attempted to find a middle way between upholding national pride, which meant appearing bellicose, and finding an acceptable compromise.  Washington was well aware of the situation.  Its agents in Mexico – William Parrot, John Black, F. M. Dimond, and others – continually informed the Tyler and Polk administrations that the saber rattling public pronouncements of Mexican leaders were all show and that the leaders were in fact seeking an honorable way out of the impasse.  In July 1845, Black reported that the Herrera administration was seeking a “substitute for war which in its opinion will save its honor,” and that Mexico had “nothing to gain and everything to lose” in a war against the United States.
That same month, Mexican General Mariano Arista reported to his superiors that his army in the north was bereft of essential provisions, indeed that his men had “almost taught themselves not to eat.”  Hungry, poorly clad, and lacking mules, horses, and military equipment, desertions were depleting the Mexican ranks.  In August, Dimond, the American consul in Veracruz, informed the Polk administration that the Mexican army on the northern frontier was in a “starving condition . . . a wretched state even for peace to say nothing of war.”  To Polk, this was good news, as Mexico’s distress made it more likely that the government would accept the exaggerated boundaries of Texas and sell its northern territories to the United States; or failing that, Mexico’s military weakness would allow the U.S. to quickly gain the upper hand in a war.[16]

President Polk’s expansionist strategy

Sarah and James Polk

Sarah and James Polk

The historian Amy S. Greenberg describes James K. Polk as a protégé of Andrew Jackson, a hardworking president, a devoted husband to his wife, Sarah, and a slaveholder who brought his slaves to the White House in 1845.  He was ambitious, meticulous, secretive, and strategic, the latter being essential for realizing his expansionist goals in a complex diplomatic and political environment.  Polk undertook two very different approaches toward Great Britain and Mexico.  Toward Great Britain, he feigned war while pursuing a negotiated settlement on the division of the Oregon territory.  Toward Mexico, he expressed peaceful intentions while actively preparing for war, his goals being not only to obtain the expansive border claims of Texas but also the Mexican territories of California and New Mexico.  Although Polk said nothing about California on the campaign trail, he confided to his cabinet in the first days of his presidency that the acquisition of California was one of his main objectives.  The territory had fertile lands, rich deposits of minerals, and fine harbors that would facilitate the expansion of trade across the Pacific Ocean.

With regard to the Oregon territory, Polk encouraged the saber-rattling rhetoric of “Fifty-four forty or fight!” (referring to the upper latitude of the jointly held Oregon territory) in order to pressure Great Britain to back down on its proposed dividing line of the Columbia River.  Polk wanted the boundary further to the north and suggested to the British the 49th parallel, which was far below 54-40 latitude.  According to William Weeks:

He fomented Democrats from the Northwest such as Edward Hannegan of Indiana and William Allen of Ohio to demand all of Oregon, assuring them that he would never back down from the claim to 54-40 even though he planned all along to use their extreme claims to form the basis of a compromise at 49 degrees. . . . Here the president benefited from the demonstrated willingness of Americans to fight even when a lack of preparedness and plain common sense seemed to preclude that option, and indeed, the chest-thumping assertions of Hannegan, Allen, and others bore some resemblance to the War Hawks of 1812.  Polk, unlike Madison, was not controlled by hotheads in Congress but rather used their threats to help extract a deal.[17]

Polk concluded the Oregon deal in June 1846, two months after the U.S. went to war against Mexico.  The Oregon Treaty established the border at the 49th parallel, with the British keeping Vancouver Island.  Polk thus got what he wanted, even if his expansionist allies were disgruntled at the compromise.  Polk’s militant posturing had pressured Great Britain to agree to a boundary line north of the Columbia River, but he knew that if he pushed too hard, Great Britain could ally itself with Mexico against the U.S., thus creating a formidable barrier to his plans for California.

Polk’s strategy toward Mexico was just the opposite of his strategy toward Great Britain and Oregon.  Instead of talking loudly and negotiating quietly, Polk talked softly and struck with force.  Prior to the onset of war, Polk promised the American people that any expansion of the nation’s boundaries into Mexican territory would be undertaken “not as the conquest of a nation seeking to extend her dominions by arms and violence but as the peaceful acquisition of a territory once her own.”  At the same time, he began preparing for war, sending U.S. forces into the disputed territory and reinforcing naval squadrons in the Gulf of Mexico and Pacific Ocean.  How much force would be needed to convince the Mexican government to give up its northern territories could not be foretold.  In November 1845, he sent emissary John Slidell to Mexico City, ostensibly to negotiate with the Mexican government but actuality to demand that Mexico accept the exaggerated border claims and sell Alta California and Nuevo México.  As Weeks notes:

If Polk bluffed war and sought peace with Great Britain, it was very much the reverse as concerns the Republic of Mexico. . . . First, he had to appear to try to resolve the differences with Mexico via negotiation.  To that end, he dispatched John Slidell of Louisiana to Mexico City to negotiate the range of issues separating the states.  In truth, Slidell went not to negotiate but to dictate.  He demanded that Mexico drop its protests against the annexation of Texas, recognize its boundary at the Rio Grande del Norte, and agree to sell California ($25 million) and New Mexico ($3 million) to the United States.  In exchange for these extravagant demands, the Polk administration stood ready to assume the nearly $2 million in Claims that American citizens held against the Mexican government for private property seized during the course of the numerous revolutions since 1821.[18]

General Taylor’s camp at Corpus Christi

Polk began military maneuvers in July 1845.  Without authorization from Congress, he directed General Zachary Taylor and 4,000 troops to advance to the south bank of the Nueces River, near Corpus Christi.  Six months later, on January 13, 1846, before learning of the outcome of John Slidell’s mission in Mexico City, Polk ordered Taylor to proceed further to the Rio Grande, thus entering disputed territory.  As Polk later wrote in his diary, he anticipated “a collision between the American and Mexican forces.”[19]  Taylor’s troops set up camp on the north side of the Rio Grande, opposite the town of Matamoros, on March 28.  They built a makeshift fort, aimed their artillery at the town, and blockaded the mouth of the river, denying food and supplies to 4,000 townspeople and 3,400 Mexican soldiers stationed there.  Apart from entering into what Mexicans considered their territory, the blockade itself was an act of war.  According to the historian Glenn Price:

The first indisputable act of war was an act of the United States, when its naval forces blockaded the Rio Grande on 12 April 1846.  Even had the land on the left bank of that river been within the limits of the United States, to blockade the river, which in that case would have been the international boundary, was an act of war.  That conclusion needs no supporting argument, but it may be of interest to point out that the United States government was on record as stating that any attempt by Mexico to close the river to American traffic would justify hostilities.  Instructions given General Zachary Taylor by the Department of War stated that “the Rio Grande, in a state of peace, may be regarded as equally open to navigation of the U.S. & Mexico,” and should this “reciprocal right be resisted by Mexico,” Taylor was at liberty to force it open by military power.[20]

Onset of war

Mariano Paredes y Arrillaga

Mariano Paredes y Arrillaga

General Mariano Paredes y Arrillaga replaced Herrara as president of Mexico in December 1845.  He immediately found himself in the same dilemma as his predecessor, having no means of stopping the United States from moving into (disputed) Mexican territory while nonetheless being pressured by the public to uphold national honor and exert a valiant defense of the homeland.  Paredes dismissed Slidell in March 1846, explaining to him that the presence of American troops on Mexican soil made negotiations impossible.  Slidell also lacked proper credentials and had come with an additional agenda other than negotiating the border dispute.  Paredes demanded that U.S. forces return to the north side of the Nueces River, but he nevertheless sought to reassure the U.S. of his intentions by issuing a manifesto declaring that he “would never commit a single aggression against the United States,” but only act in defense of Mexico.[21]

Battle of Palo Alto, May 8, 1846

On April 23, with the American troops encamped opposite Matamoras and having blockaded the river, Paredes issued another manifesto, this time declaring that “from this day defensive war begins.”  The following day, the Mexican commander at Matamoros, General Arista, informed Taylor that hostilities had commenced.  On April 25, Mexican troops crossed the river and attacked a U.S. patrol unit, killing eleven men.  Full-blown battles followed at Palo Alto and Resaca de la Palma on May 8 and 9, both of which U.S. forces won.

Lieutenant Ulysses S. Grant later recorded in his Personal Memoirs, “We were sent to provoke a fight, but it was essential that Mexico should commence it,” otherwise it “was very doubtful whether Congress would declare war.”  Lieutenant Colonel Ethan Allen Hitchcock of Vermont, the grandson of Revolutionary War hero Ethan Allen, an assistant professor of tactics at West Point, and a close friend of General Taylor’s, wrote in his diary at the time of the “impudent arrogance and domineering presumption” of the Polk administration’s assertion that the Texas-U.S. boundary extended to the Rio Grande.  “The claim,” he wrote, “is without foundation.”[22]
News of the first skirmish reached Washington on Saturday, May 9.  President Polk was at the time preparing a war message to Congress based on Mexico’s refusal to receive John Slidell.  With the outbreak of fighting, Polk had what he wanted.  He could now claim that “American blood had been spilled on American soil,” and thus that the United States was fighting an honorable, defensive war.  “To Polk,” writes Weeks, “the fiction of Mexican aggression had to be staunchly maintained so as to justify a cession of territory as punishment.”[23]
US House of Representatives

US House of Representatives

On Monday, May 11, President Polk presented his war message to Congress.  He blamed Mexico for the outbreak of hostilities and declared that he had done everything in his power to avoid war.  He did not ask Congress for a formal declaration of war, as required in the Constitution, but stated that war already existed and asked Congress for money to supply troops in the field.  Representative Linn Boyd, Democrat of Kentucky, introduced an amendment to the war bill paraphrasing the president, declaring that “a state of war existed” between Mexico and the United States.”[24]

Objections were immediately raised.  Whig Representative Robert Toombs of Georgia charged the president with “usurping the war making power” of Congress as well as “seizing a country” not our own.  South Carolina representative Isaac E. Holmes, a Democrat, argued that the outbreak of fighting did not mean that war had broken out, as only Congress could declare war.  He noted that in 1807, the British warship Leopard had fired on the U.S. warship Chesapeake, killing a number of Americans, but that this attack had not resulted in war; nor should the outbreak of hostilities in Texas.  Holmes’ Democratic colleagues did not agree, however, and Boyd’s amendment passed by a partisan vote of 123-67.  A similar amendment introduced in the Senate passed by a vote of 28-18.[25]
Rep. Joshua Giddings

Rep. Joshua Giddings

Representative Joshua Giddings of Ohio, an abolitionist and ally of John Quincy Adams, refused to be intimidated into voting for Polk’s war bill on the skewed basis of providing for troops in the field.  He charged that Polk’s aggressive maneuvers were designed to provoke a war with Mexico and that Polk’s ultimate goal was the conquest of Mexico and California.

In the murder of Mexicans upon their own soil, or in robbing them of their country, I can take no part, either now or hereafter.  The guilt of these crimes must rest on others; I will not participate in them; but if Mexicans or any other people should dare invade our country, I would meet them with the sword in one hand and a torch in the other . . . We may always justify ourselves for defending our country, but never for waging a war upon an unoffending people for the purpose of conquest.  There is an immutable, an eternal principle of justice pervading the moral universe.  No nation, or people, or individual ever did or ever will violate that law with impunity.[26]

Senator Thomas Clayton

The Senate debated the war bill for two days.  Senator Thomas Clayton of Delaware, a Whig, laid out the main arguments of opponents; namely, that the president had initiated hostilities without consulting Congress and that moving U.S. forces into disputed territory was an act of aggression on the part of the U.S.:

I do not see on what principle it can be shown that the President, without consulting Congress and obtaining its sanction for the procedure, had a right to send an army to take up a position, where, as it must have been foreseen, the inevitable consequences would be war. . . . The question is, Was it proper?  Was it right?  . . . Why was it necessary to cross the desert, and take up a position immediately in front of the friendly town of Matamoros?  Why was it necessary to take up that position, with the batteries pointed against the town at a distance of not more than five hundred yards from its environs?  It was an aggressive act; an act which the civilized world will designate.  It was as much an act of aggression on our part as is a man’s pointing a pistol at another’s breast. . . . I have felt that these acts of the Executive ought to be condemned – I do condemn them.  I think that they will be condemned by the people of the United States.  By these acts we have been precipitated into a war with a friendly nation.[27]

In the end, the Senate voted 40-2 to approve supplies for the troops (coupled with the acknowledgement that war existed), and the House voted 174-14, with 35 abstentions.  These tallies, however, hardly reflected the strength of the opposition.  As the historian John H. Schroeder explains:

As sensitive politicians, most administration critics could not vote their consciences at the expense of their patriotism.  Because they understood that national public opinion would be outraged and demand retribution for the attack on the Rio Grande, the opposition dared not risk charges of failing to support an endangered American army.  That fear of being labeled disloyal was the foremost consideration in the minds of dissidents.[28]

In presenting his war bill to Congress, Polk made no mention of his desire to obtain California and New Mexico.  According to the historian Ballard C. Campbell, Polk’s “interest in using the war for territorial gain was not publicly disclosed until August 1846, when the president asked Congress to approve a $2 million appropriation that could be used as partial payment to Mexico for territory – or perhaps a bribe to Santa Anna.”[29]

Indeed, on July 6, an agent of Polk, Alexander Slidell Mackenzie, the nephew of John Slidell, met secretly with Santa Anna in Havana, where the latter was living in comfortable exile.  Mackenzie conveyed to him that President Polk would assist his return to power in exchange for negotiating the cession of the disputed border area and at least part of California, for which Mexico would be liberally paid.  Mackenzie came away from the three-hour meeting believing that he had succeeded in his mission.  Santa Anna was subsequently allowed to pass through the U.S. naval blockade and return to Mexico.  Rumors that Santa Anna intended to sell out his country followed him into Mexico City, but he proved them wrong, gathering together a new army to repel the invaders.  Polk had been duped.[30]

Underlying causes:  race, history, and “Manifest Destiny”

President Polk needed Mexico to strike the first blow not only for the purpose of convincing Congress to enact a war bill, but also to rouse the American public.  This was essential if the U.S. was to prosecute a successful war.

Recruitment poster, Boston

The U.S. Army had less than 7,400 soldiers in early 1846.  The war bill passed by Congress on May 13, 1846, authorized the president to enlist 50,000 “volunteers” for twelve months.  Many young men jumped at the opportunity, egged on by the pro-war press.  Walt Whitman, the 27-year old editor of the Brooklyn Daily Eagle and later a famed poet, called for revenge against Mexico in an editorial on May 11, 1846:

Yes: Mexico must be thoroughly chastised!  We have reached a point in our intercourse with that country, when prompt and effectual demonstrations of force are enjoined upon us by every dictate of right and policy. . . . Let our arms now be carried with a spirit which shall teach the world that, while we are not forward for a quarrel, America knows how to crush, as well as how to expand![31]

The desire to “crush” Mexico had racial, historical, and ideological overtones.

Most Anglo Americans viewed Mexicans as an inferior race based on their mixed, Spanish-Indian ancestry.  While not scorned as “savages,” they were depreciated as “an idle, thriftless people” who did not deserve to rule over the lands they held in North America.[32]  Some viewed the inability of Mexicans to pacify hostile tribes as confirmation of their inferiority.  Perpetual disorder in the Mexican government furthermore prompted predictions that Americans would one day rule Mexico.  William Seton “Guy” Henry, an American journalist who covered the war, wrote of the Mexican people:

The finger of Fate points, if not to their eventual extinction, to the time they will cease to be the owners of the soil, and when the Anglo race will rule with republican simplicity and justice, a land literally “flowing with milk and honey” – who will, by their superior mental and physical abilities . . . populate the country with a race of men who will prove the infinite goodness of our Maker, in creating nothing but what is for use and some good purpose.”[33]

Recruitment poster, Holmes County, Ohio

Anglo American racism created substantial barriers to peacefully resolving outstanding issues with Mexico through negotiations.  Not only was there a widespread belief among Americans that the “inferior” Mexican people must sooner or later give up their lands to the superior “Anglo race,” but the very idea of sitting down at a table and talking as equals was anathema to many.  According to Glenn Price, “The attitude was that there was very little difference between an Indian and a Mexican; serious and respectful diplomacy was out of place in either case.”[34]  For Polk and many other Americans in that intensely racist era, the mere fact that brown-skinned Mexicans expected to be treated as equals constituted a challenge to the assumed racial hierarchy of Anglo (white) dominance.  Polk and company expected Mexicans to accept their status as an “inferior race” and give in to the demands of the “superior race.”  Indeed, Mexico’s failure to do so was deemed a sufficient cause for war.  According to the historian Amy Greenberg, “Polk viewed international relations through the lens of slaveholding and dominance”:

Polk’s concept of justice was unquestionably shaped by his experience as a slavemaster.  Some slaveholders, such as Henry Clay, or Thomas Jefferson a generation before, struggled with the knowledge that slavery was wrong.  But like most intensely conservative slave masters in the 1840s, Sarah and James Polk believed the domination of white over black was part of God’s plan. . . . Domination of the strong over the weak, and white over black or brown, was not just the reality of slavery, it was also, in their perspective, right.[35]

Of course, there is a long history of one group dehumanizing another when desirous of their land.  The English did it to the Irish in the mid-16th century, depreciating them as pagans (most were Catholic) and savages who improperly used their lands, which British lords proceeded to take over.  Andrew Jackson did much the same in the 1830s, labeling the peaceful Indians of the Southeast “savages” and declaring his intention to “reclaim them from their wandering habits,” despite the fact that they had taught Virginia settlers how to grow corn.  During the U.S.-Mexican War, the refrain of Anglo-Saxon superiority followed every American victory.  When General Taylor captured the Mexican town of Monterrey in September 1846, for example, Walt Whitman described it as “another clinching proof of the indomitable energy of the Anglo-Saxon character.”[36]

“Let the half-civilized Mexicans hear the crack of the unerring New Hampshire riflemen.”

Outspoken Anglo American racism coupled with American aggression evoked fear in Mexico.  The editors of a Chihuahua newspaper expressed the view in 1841 that if Mexico failed to stop the United States from annexing Texas, Anglo Americans would not only gobble up more Mexican territory but also establish a different religion on Mexican soil and sell Mexican citizens “as beasts” because “their color was not as white as that of their conquerors.”  The editors of El Siglo Diez y Nueve wrote in May 1844 that the United States was populated by a “race that had no mercy for others.”  They pointed out the hypocrisy of Americans proclaiming liberty for all while annihilating Indians and enslaving Blacks.  The Americans, warned El Siglo, would not be content with merely acquiring Mexican soil; they would only be satisfied when the “Mexican race” was destroyed.[37]  Such views explain why many Mexicans demanded that their government fight the U.S. despite Mexico’s military weakness, rather than give in to American aggression.

The American desire to “crush” Mexico was also rooted in the historical memory of Mexican atrocities committed at the Alamo and Goliad.  Similar atrocities committed by U.S. soldiers at San Jacinto were forgotten or viewed as just revenge.  According to the American military historian John Eisenhower:

During the nine years between the Battle of San Jacinto and the U.S. offer of annexation to Texas, the government of the United States always maintained a proper neutrality between Texas and Mexico.  The American people, however, observed no such inhibitions.  They openly sympathized with the Anglo-Saxon émigrés whom they now considered Texans; they supplied Sam Houston’s army with weapons; and though brutality occurred on both sides, the Americans sided with the Texan version on every controversial issue.  As a result the American public grew progressively more antagonistic toward Mexico as a nation.  Mexicans came to be considered less than “civilized” people, undeserving of rights generally accorded to Europeans.  It is not surprising, therefore, that rationalizing unjust acts against Mexico would become easy.[38]

John O"Sullivan

John O”Sullivan

A third factor influencing American attitudes toward Mexico was the ideology of “manifest destiny,” which combined religious, political, and racial ideas into a righteous justification for American territorial expansion.  The most famous proponent of this informal ideology, John O’Sullivan, editor of the United States Magazine and Democratic Review, expressed the view that U.S. expansion was divinely ordained; that it would extend freedom, democracy, and civilization to new lands; and that more land was needed for a rapidly growing Anglo-Saxon population.  In asserting this presumed mandate from heaven, O’Sullivan made the case that America represented a new order of civilization, as compared to Old World empires, and that the American character was inherently noble and good.  As he wrote in 1839:

What friend of human liberty, civilization, and refinement can cast his view over the past history the monarchies and aristocracies of antiquity, and not deplore that they ever existed?  What philanthropist can contemplate the oppressions, the cruelties, the injustice inflicted by them on the masses of mankind, and not turn with moral horror from the retrospect? America is destined for better deeds.  It is our unparalleled glory that we have no reminiscences of battle fields but in defense of humanity, of the oppressed of all nations, of the rights of conscience, the rights of personal enfranchisement.  Our annals describe no scenes of horrid carnage where men were led on by hundreds of thousands to slay one another, dupes and victims to emperors, kings, nobles, demons in the human form called heroes.  We have had patriots to defend our homes, our liberties, but no aspirants to crowns or thrones, nor have the American people ever suffered themselves to be led on by wicked ambition to depopulate the land, to spread desolation far and wide, that a human being might be placed on a seat of supremacy.[39]

This flattering view of American history and identity ignored much actual history, including the recent forced removal of Native American tribes that caused thousands of deaths.  Nor was it true that democratic governments eschewed aggression and imperialism.  George C. Herring comments:

Dubious when it was written, O’Sullivan’s affirmation soon proved completely wrong.  The Mexican-American conflict of 1846-48 was in large part a war of lust and aggrandizement.  The United States had long coveted Texas.  In the 1840s, California and New Mexico also became objects of desire.  With characteristic single-mindedness, Polk set his sights on all of them.[40]

The United States, in other words, was becoming more like Old World empires, except that a president rather than a king was leading the nation into “scenes of horrid carnage.”  O’Sullivan coined the particular catchphrase “manifest destiny” in the July-August 1845 issue of the United States Magazine and Democratic Review, just after Texas was annexed to the U.S.  The slogan was quickly picked up by other expansionists who used it to embellish American territorial ambitions with noble ideals.  One such expansionist was the president of the United States, James Polk.  In his Third Annual Message to Congress on December 7, 1847, he said:  “No country has been so much favored, or should acknowledge with deeper reverence the manifestations of the divine protection.  An all-wise Creator directed and guarded us in our infant struggle for freedom and has constantly watched over our surprising progress until we have become one of the great nations of the earth.”[41]

Elder statesman Albert Gallatin

Among those who called attention to the banality of “Manifest Destiny” was Albert Gallatin, former congressman, secretary of the treasury, and foreign minister, who wrote at the age of eighty-seven, “What shall be said of the notion of an empire extending from the Atlantic to the Pacific, and from the North Pole to the Equator?  Of the destiny of the Anglo-Saxon race, or its universal monarchy over the whole of North America?”  Such “allegations of superiority of race and destiny neither require nor deserve any answer; they are but pretenses under which to disguise ambition, cupidity, or silly vanity.”[42]  Abolitionists also held forth a different vision the nation’s progress, one that extended freedom and democracy to three million people enslaved in the United States.  Peace advocates, too, conceived of progress in different terms.  They envisioned a time when war would be transcended through “the general use of conciliation, arbitration, judicial methods, and other peaceful means of avoiding and adjusting differences among nations,” as stated in the 1828 charter of the American Peace Society.[43]

In short, not all Americans believed that their nation’s providential mission lay in conquest and imperial power.  A sizable minority refused to accept the idea that the United States must follow in the footsteps of Old World empires.  Their vociferous protests against the U.S.-Mexican War indicate that many people recognized and wrestled with moral choices in their day.  It was not fate or some elusive concept of “manifest destiny” that led the U.S. into war in 1846, but Mr. Polk and the militant expansionists.
Could war have been avoided?  Surely it could, had Polk been willing to compromise with Mexico as he did with Great Britain.  Had John Slidell gone to Mexico City “in a true spirit of amity and conciliation,” as suggested by Clay, and had Polk not initiated aggressive war maneuvers, negotiations with Mexico over the disputed territory would likely have succeeded.  The Mexican government, for its part, could have recognized Texas independence early on, accepting the loss of territory.  Whether or not the United States could have obtained California without war is a more difficult hypothetical question.  That Mexico might have been willing to sell all or part of California is indicated by the fact that, in 1846, Santa Anna offered to cede Alta California to Great Britain in an attempt to keep it out of American hands.  The British declined the offer and encouraged Mexico to settle its differences with the United States.  Given Mexican fears of racially-charged Anglo imperialism, the U.S. might have offered an accompanying non-aggression treaty.

III.  Costs and conduct of the war

After receiving the casualty report from the Battle of Buena Vista, the Philadelphia North American editorialized on November 11, 1846, “Wars are always popular at a distance.  The bulletin that announces the destruction of a thousand fellow beings is received with . . . pride, pomp and circumstance of a glorious war. . . . Let our people realize the price paid for conquered provinces and military glories.”[44]  No doubt, many did realize that day the price paid for conquest.  Yet the tendency to glorify war, celebrate victories, and make heroes of commanding officers remained steadfast throughout the war.  Whig politicians who opposed the war were as eager as Democrats to honor American warriors.  Indeed, they selected General Zachary Taylor as their presidential candidate in 1848.

War news from Mexico (1851 hand-colored engraving by Richard Caton}

The U.S.-Mexican War was documented like no other war in history up to that time.  At least eighteen American journalists were embedded in U.S. Army units during the war.  Hundreds of soldiers wrote letters and dozens were christened “occasional” or “special” correspondents for mass circulation newspapers.  Americans also established newspapers in occupied Mexican cities.  The public’s demand for eyewitness accounts of battles and first hand news of the war was insatiable.  Even antiwar editor Horace Greeley of the New York Tribune felt obliged to print every detail of battle, as “carnage” is what sold newspapers.  Newspapers also published lists of casualties, often gathered by journalists, which were more fearfully awaited.  News from Mexico took at least ten days to reach New Orleans, after which it was distributed by steamship, rail, or horseback to other cities (telegraph lines were in their infancy).  It took another eight days to reach Washington from New Orleans.[45]

American journalists and soldier correspondents typically praised American courage in the field and exulted over American victories, but they also described the dreary and brutal reality of the war:  debilitating diseases in the camps, inadequate provisions, disorderly conduct, conflicts between soldiers and officers, desertions, American atrocities against Mexican civilians, and persistent Mexican guerrilla attacks that made it all-but-impossible for soldiers to celebrate their battle victories. The glorification of war, as such, was tarnished by the reality of it. 
Three weeks after the first major battles of the war at Palo Alto and Resaca de la Palma, Christopher Haile of the New Orleans Picayune walked through the battlefield and reported on the scene.  “Rather than recount the battle,” writes the historian Michael Scott Van Wagenen, “he discussed the ‘feelings of deep sadness’ and horror he felt on visiting these places.  Palo Alto turned particularly dramatic when the party stumbled across the remains of Mexican casualties of Taylor’s artillery that had been mummified by the sun.  He spared no detail in describing the mangled bodies and the ‘countenance which their death agonies had stamped on them.’”  More typically, it was American casualties that tore at the hearts of Americans.  As these casualties mounted, public enthusiasm for the war rapidly diminished.  By the end of 1846, the initial rush of volunteers had slowed to a trickle and few were interested in re-enlisting after their term of duty ended.[46]
Literate U.S. Army regulars

Literate U.S. Army regulars

About 90,000 U.S. soldiers served in Mexico during the war; no more than 43,000 at any one time.  Approximately 31,000 were Army regulars while 59,000 were part of “volunteer” state regiments.  About 40% of the regulars were immigrants, mainly Irish.  According to records of the U.S. General Recruiting Service for 1840-49, 35% of the regulars could not sign their own names.  All black men were excluded from the U.S. Army, while the U.S. Navy imposed a quota of five percent.  Black servants were nonetheless part of many army units.  Lieutenant Ulysses S. Grant wrote from New Orleans to his fiancé, Julia Dent, “I have a black boy to take along as my servant that has been in Mexico.  He speaks English, Spanish and French.  I think he may be very useful where we are going.”  Some southern officers brought their slaves with them and some northern officers employed slaves as their servants.  Although not formally enrolled as soldiers, some servants took part in battles and were wounded.  A few escaped in Mexico.[47]

The regulars received low pay and were subject to harsh discipline.  Volunteers also received low pay but the discipline was light, if not woefully lacking.  Some volunteers signed up for three month terms, which hardly allowed for training and regimentation (the federal government later required 12-month terms).  Many volunteer regiments elected their own immediate officers “and expected to be treated as citizens, if not heroes,” according to the historian Paul Foos.[48]  The regulars, however, proved to be the more disciplined and effective soldiers.  “Zachary Taylor, who found the volunteers impossible to control, believed them more trouble than they were worth,” writes Greenberg.  “Perhaps he was right.  Volunteers, lacking both training and discipline, were not only less reliable under fire than the regulars, and disproportionately susceptible to communicable disease, in part because of poor sanitation practices, but also committed atrocities against Mexican civilians that would come to shock Americans back home.”[49]

Casualty list in the Charleston Courier (click to enlarge)

The casualty rate for soldiers was extremely high on both sides.  Of the 90,000 U.S. soldiers who served in Mexico, nearly 14,000 died, a death rate of 15.5%, or one out of every seven soldiers.  According to Eisenhower, this was “the highest death rate of any war in our history.”[50]  On the Mexican side, the death rate was even higher, although figures are less precise.  Of some 82,000 men who served in the Mexican army or were guerrillas, an estimated 25,000 lost their lives, an astounding death rate of 31%, or almost one out of every three soldiers.  These figures do not include Mexican civilian deaths, the number of which is unknown.  As Mexican armies included many women and wives who assisted the soldiers, they were subjected to the travails of exposure, hunger, and disease as well.[51]

American casualties

  • Total number of U.S. soldiers who served in Mexico:  89,836 (Regulars: 31,024; Volunteers: 58,812)
  • Deaths during the war:  13,962 (15.54%)
  • Killed in action or died of wounds: 1,733
  • Died of disease or other causes:  12,229
  • Wounded:  4,152

Mexican casualties

  • Total number of Mexican soldiers mobilized:  82,000
  • Total number who died during war:  25,000 (30.5%)
  • Killed in action or died of wounds:  5,000
  • Died of disease or other causes:  20,000
  • Missing:  10,000

Disease was the biggest killer in the war.  For every U.S. soldier who died in battle or from battle wounds, seven died of disease.  “As was typical for other 19th-century conflicts,” writes the American military historian Derek R. Mallett, “infectious disease accounted for far more deaths than battle trauma.  Yellow fever, malaria, dysentery, and epidemic measles, mumps, and even occasional smallpox were problems both on campaign and in camp.”[52]  Much illness resulted from drinking tainted water from polluted streams, a situation exacerbated by a shortage of wood to make fires and boil water.  Soldiers also needed better tents and medical care.  This became apparent during the nine months that General Taylor’s troops spent camping near Corpus Christi (July 1845 to March 1846).  According to Foos:

Dysentery and fevers raged through the camp until one-sixth of the men were on sick report, and about one-half suffered from some degree of infirmity.  The tents provided by the Quartermaster’s Corps were worn and rotten . . . The border region suffered from frequent “northers,” fierce storms that could drop the temperature from ninety degrees to below freezing in a matter of hours.  The men slept in mud and cold water, the quartermasters having neglected to provide floors for the tents.[53]

To these indignities were added late pay from the Quartermaster and swarms of “camp followers” – liquor sellers, gamblers, prostitutes, and criminals – intent on quickly relieving soldiers of their pay, and sometimes robbing and assaulting them.  Taylor could do little to disperse this rabble in Corpus Christi as civilians were subject only to civil authority.  Desertions were common on both sides.  The number of U.S. deserters is estimated at 9,200, about ten percent of the regulars and nearly seven percent of the volunteers.[54]  This is the highest desertion rate in any American war.

Desertions from the Mexican Army were likely greater.  On one grueling 250-mile march from San Luis Potosí to Buena Vista (near Saltillo) in February 1847, General Santa Anna lost nearly 5,000 soldiers to desertion or death.  Desertions in the U.S. were not sparked by fear of battle but by intolerable living conditions, disease, harsh discipline, and sometimes anti-Catholic prejudice.  The Second Pennsylvania Regiment, while still in New Orleans, lost fifty-nine men to desertion, about six percent of its soldiers.  In early 1847, forty South Carolina volunteers aboard a riverboat heading for Mobile mutinied.  “With fixed bayonets, they stopped the boat and went ashore,” having endured two days below deck without food, according to the American historian Ernest Lander.  “No one would obey the officers’ orders to arrest the mutineers; hence the officers yielded and hushed up the affair.”[55]

Commemorative plaque in Mexico City honoring 71 members of the San Patricio Battalion

The most famous, or infamous, of the American deserters was John Riley, a recent Irish immigrant and former non-commissioned officer in the British Army.  Troubled by a war against fellow Catholics, and offered incentives to defect by Mexican authorities, Riley and forty-eight soldiers, mostly Irish-American, deserted General Taylor’s camp across from Matamoros before the first shot was fired.  Joined by other Irish and German deserters and a few escaped slaves, Santa Anna organized the soldiers into an artillery battalion in November 1846.  The San Patricio Battalion fought tenaciously in battles at Monterrey, Buena Vista, Cerro Gordo, and Churubusco.  The U.S. Army captured and executed fifty members of the battalion, but Riley’s life was spared, as he had deserted before the war officially began.  His punishment consisted of being whipped and branded with a “D” on his face.  The San Patricio Battalion has been honored in Mexico in commemorations and on St. Patrick’s Day.  In 2002, Mexico’s Chamber of Deputies inscribed in gold letters on its Wall of Honor, “Defensores de la Patria 1846-1848 y Batallón de San Patricio” (Defenders of the Motherland 1846-1848 and the San Patricio Battalion).

Mexican lancers and infantry

Mexican lancers and infantry

Mexican troops often outnumbered U.S. troops on the battlefield but failed to win a single major battle in terms of forcing an American retreat.  The Mexican army had antiquated short range artillery and often ran short of ammunition.  American long-range artillery eviscerated Mexican units at a distance and thwarted Mexican charges.  The U.S. Army also had more highly trained officers and engineers, and was far better supplied than Mexican forces, notwithstanding many limitations.  Mexican troops were literally starving at times.

Unable to defeat the Americans in pitched battles, Mexican fighters resorted to guerrilla warfare.  This asymmetrical warfare consisted of attacking small groups of U.S. soldiers, plundering supply trains, disrupting communication lines, and making travel unsafe except in large armed groups.  The guerilleros or rancheros, as they were called, also took revenge against Mexicans who accommodated the American invaders. U.S. commanders treated the guerrillas as outlaws rather than soldiers, denouncing them as “atrocious bands” that “violate every rule of warfare observed by civilized nations.”[56]  Mexicans could also make claims on the unwritten rules of civilized warfare, as the abuse of Mexican civilians began as soon as the Americans set foot in Matamoros in May 1846.
Apart from guerrillas, prisoners-of-war were generally treated decently by each side.  Almost all were paroled within a short time.  Parole was a widely used practice in which prisoners were allowed to go home under an oath not to bear arms for the duration of the war, or until exchanged for prisoners held by the other side.  This was not an undesirable outcome for many soldiers.  For the U.S., paroling Mexican prisoners was a necessary measure, as the U.S. Army could not afford to feed, house, and guard thousands of Mexican prisoners – and the U.S. captured many more Mexican prisoners than the other way around.  In paroling Mexican prisoners quickly, President Polk also hoped to gain favor with the Mexican public and counter the “prejudice” of Mexican newspapers toward the American invaders.  On July 9, 1846, he ordered General Taylor to interact with captured Mexican officers and inform them of the willingness of the United States to establish an “honorable peace.”[57]  Such efforts to win favor with the Mexican people and convince them of America’s good intentions were fundamentally at odds with the basic mission of the war, which was to conquer and break the will of the Mexican people and government.

Military campaigns and occupations

4_miltary_MexAmerWar1846-48-eThe Polk administration’s military strategy was subordinate to its political strategy of persuading Mexico to sell or cede the territories of Nuevo México and Alta California.  President Polk did not initially plan to conquer Mexico City, nor engage in a lengthy war of occupation.  His three-part strategy involved:
  • directing General Zachary Taylor to take control of the northeastern region of Mexico, beginning with the town of Matamoros;
  • sending Colonel Stephen W. Kearny and some 1,600 soldiers from Fort Leavenworth, Kansas, to secure the northern territories of Nuevo México and Alta California, and dispatching naval forces in the Pacific to assist in the capture of California; and
  • ordering a naval blockade of Mexico’s Gulf ports so as to deprive the central government of its major source of revenue, import duties.
Polk decided on the invasion of central Mexico in November 1846, following General Taylor’s capture of Monterrey and the Mexican government’s continued refusal to acquiesce to U.S. demands.  The invasion, led by General Winfield Scott, began with the bombardment and takeover of Veracruz in March 1847 and ended with the fall of Mexico City in September, although the vicissitudes of occupation continued.  U.S. forces finally withdrew in July 1848, after the Treaty of Guadalupe Hidalgo had been signed and ratified by both countries.
 Major battlesDatesU.S. commander
Palo Alto & Resaca de la PalmaMay 8-9, 1846Zachary Taylor
MontereySept. 21-23, 1846Zachary Taylor
Buena VistaSept. 21-23, 1846Zachary Taylor
ChihuahuaFeb. 28, 1847Alexander Doniphan
VeracruzMar. 22-26, 1847Winfield Scott
Cerro GordoApr. 17-18, 1847Winfield Scott
Contreras & ChurubuscoAug. 18-20, 1847Winfield Scott
Occupying a foreign country was something new in American foreign policy.  Although U.S. forces repeatedly invaded British Canada during the War of 1812, they occupied only one small section of Upper Canada at the end of the war – and had to give that up in the peace treaty.  The invasion of Spanish Florida by General Andrew Jackson in the First Seminole War succeeded in pressuring Spain to transfer Florida to the United States, but Jackson’s forces did not remain to occupy the peninsula.

Popular U.S. culture thrived on stories of American heroism and Mexican treachery, eliding the fact that U.S. troops were invading and occupying Mexico

The American occupation of Mexico was accompanied by much abuse and violence against Mexican civilians.  This violence falls into four categories:

  • Personal violence – the abuse of civilians by individual soldiers, including robbery, rape, and murder.  This unscripted, wanton violence was especially prevalent in Taylor’s northeastern campaign, despite efforts by U.S. officers to stop it.
  • Counter-insurgency violence – the extension of anti-guerrilla operations to civilians, including revenge attacks, torture, and intimidation; aimed at negating civilian support for guerrillas and extracting information as to their whereabouts.  As guerrilla warfare was deemed outside the rules of civilized combat, special U.S. counterinsurgency units engaged in “uncivilized” methods with tacit approval by commanders.
  • Collateral war violence – war operations such as bombardments and sieges of cities that result in extensive civilian casualties and property damage.  The U.S. bombardment of Veracruz under General Scott stands out as one of the more egregious examples of “collateral damage,” as hundreds of civilians were killed or wounded.
  • Structural violence – official policies that impoverish, oppress, or humiliate the civilian population, including taxing the population to support the U.S. occupation and imposing martial law.  Both Taylor and Scott imposed martial law on Mexican towns but, to their credit, refused to take provisions from the civilian population without paying for them.
In general, the harsher the measures employed against Mexican civilians, the greater the popular resistance to the American occupation.  It was thus a matter of American military security to prevent violence against Mexican civilians.  Yet a war of conquest and occupation, imposed no less by undisciplined volunteers, does not easily conform to civilized rules of military engagement.

General Taylor and the occupation of northeastern Mexico

Major-General Zachary Taylor

Major-General Zachary Taylor

General Zachary Taylor’s occupation of northeastern Mexico began on May 18, 1846, when his troops crossed the Rio Grande and took control of Matamoros unopposed.  The Mexican army led by General Arista had retreated to the interior the night before, being short of every kind of provision.  In June, Taylor began receiving reinforcements, mainly volunteer regiments, in anticipation of moving on to other towns.  He waited until August for the arrival of steamboats to move his troops and supplies to Camargo, 80 miles upriver.  The waiting period proved hazardous for the 4,000 residents of Matamoros.  According to the U.S. Army military historian General John S. Brown:

As the boredom of garrison duty began to set in, plundering, personal assaults, rape, and other crimes against Mexicans quickly multiplied.  During the first month after the volunteers arrived, some twenty murders occurred.  Initially, Taylor seemed uninterested in devising diversions to occupy his men and failed to stop the attacks.  As thefts, assaults, rapes, murders, and other crimes perpetrated by the volunteers mounted and Taylor failed to discipline his men, ordinary Mexican citizens began to have serious reservations about the American invasion.  Taylor’s lackadaisical approach to discipline produced an effect utterly unanticipated by the Polk administration, many of whose members, particularly pro-expansionists such as Secretary of the Treasury Robert J. Walker, believed that Mexicans would welcome the Americans as liberators. Instead, public opinion turned against the Americans.[58]

Town of Matamoros

Town of Matamoros

General Taylor’s inclination was to treat the Mexican population with humanity.  He ordered that provisions be purchased at full market value, thereby currying favor with the local business community.  Taylor also established a newspaper, written in Spanish and English, called Republic of the Rio Grande and Friend of the People.  Yet Taylor’s control over his volunteer units left much to be desired.  Lieutenant Ulysses S. Grant, in a letter to his letter to his fiancé, noted that a ”great many murders” had been committed against Mexican civilians in Matamoros in recent weeks, and that U.S. officers in charge had failed “to prevent frequent repetitions.”

Some of the volunteers and above all the Texans seem to think it perfectly right to impose upon the people of a conquered City to any extent, and even to murder them where the act can be covered by the dark.  And how much they seem to enjoy acts of violence too!  I would not pretend to guess the number of murders that have been committed upon the persons of poor Mexicans and the soldiers, since we have been here, but the number would startle you.[59]

News reporters caught wind of the mayhem.  In mid-July 1846, the journalist George Kendall of the New Orleans Picayune reported from Matamoros, “Several Mexicans were killed in rows last night – some say five or six – by drunken brawlers who hang about the camp of the Texans.”  Kendall’s colleague, Christopher Haile, commented on the rising attacks against the American volunteers, observing that the inhabitants “appear sullen and inclined to seek revenge . . . they hate us cordially.”  Guy Henry, a writer for the New York magazine, Spirit of the Times, offered a more sympathetic view of Mexicans after visiting hospitals in Matamoros.  “I left the hospital shocked with the horrors of war,” he wrote.  The hospitals were “filled with wounded and dying” Mexican soldiers, their amputated limbs confirming the effectiveness of American artillery at the battles of Palo Alto and Resaca de la Palma.[60]

The big story in the American press, however, was the great victory of Taylor’s “heroic little army” in these two battles.  A Illinois paper editorialized, “The prowess of our brave soldiers has made the perfidious Mexicans bite the dust.”  A South Carolina paper proudly proclaimed that “since the eventful days of our Revolutionary struggle no battle has been fought in which the heroes who march under the Star Spangled Banner, covered themselves with more glory, than did the little band who pressed forward at the command of the heroic Taylor, and charged an enemy of vastly superior numbers, in the very teeth of their roaring, death-dealing cannon!”[61]
Taylor’s reinforced army of 12,000 regulars and volunteers departed in August 1846 for Camargo.  They arrived just after a flood had contaminated the drinking water of the town.  During the next few weeks, unhealthy conditions and high heat combined to kill an estimated 1,500 U.S. soldiers.  “When the army finally marched out,” notes John Eisenhower, “only 370 of 795 Georgians were present for duty; only 324 of 754 Alabamians; 317 of 588 in the 2nd Tennessee” regiment.[62]

Mexican surrender at Monterrey

Having set up a supply depot at Camargo, Taylor’s next objective was to capture the fortified city of Monterrey, defended by 7,300 troops under General Pedro de Ampudia.  Taylor arrived with about 6,600 soldiers, having left behind 4,000 volunteers in Camargo.  The 10,000 residents of Monterrey had just celebrated the 250th anniversary of the city’s founding on September 20, 1596.  Taylor’s forces struck on September 21.  After three days of bombardment and fighting, with each side suffering some 450 casualties, Ampudia offered to surrender the city on condition that his troops be allowed to withdraw without harm and that an eight-week armistice go into effect.  Taylor accepted the terms, half-expecting that a political settlement would ensue.

President Polk was irate upon hearing the news of the armistice.  He recorded in his diary that if Taylor had imprisoned Ampudia’s army, it “would probably have ended the war with Mexico.”[63]  Polk had hoped for a knock-out blow that would force the Mexican government to relent.  Instead, the Mexican government remained intransigent on ceding its northern territories and Polk began planning for an invasion of Mexico City.  He also sent a message to Taylor to terminate the truce.  In early October, Secretary of War William Marcy furthermore ordered Taylor to “draw supplies” for our Army “from the enemy without paying for them,” and to “require contributions for its support” to the extent practicable.  Taylor wrote back that “it would have been impossible hitherto, and is so now, to sustain the Army to any extent by forced contributions of money or supplies.”[64]  He continued to pay Mexicans fair prices for necessary provisions.  This official practice, however, did not prevent individual soldiers from taking what they wanted, their low pay or late pay being a catalyst to their thievery.

Despite Taylor’s inclination to treat the population well, the American occupation of Monterrey quickly deteriorated.  Within two weeks, the governor of Nuevo León complained to General William J. Worth that American volunteers were abusing the inhabitants, even killing civilians “without mercy or reasonable motive.”  Such abuse troubled U.S. officers, who anticipated retribution.  Lieutenant George Meade, in a letter to his wife on October 20, 1846, wrote that American volunteers “have made themselves so terrible by their previous outrages as to have inspired the Mexicans with a perfect horror of them.”[65]  The retribution was not long in coming, as John Brown notes:

The local populace increasingly appeared more than willing to support and shield the guerrillas.  The volunteers’ racism, anti-Catholicism and violence provided all the motive that locals needed to oppose the American advance.  Guerrilla attacks grew more frequent after the battle for Monterrey, when Brig. Gen. William J. Worth . . . discontinued military patrols in the town for a short time, allowing a bloodletting to occur.  Observers estimated that volunteer troops killed some 100 civilians, including many who had been killed by Col. John C. Hays’ 1st Texas Mounted Volunteers.

Texas Ranger (wood engraving 1848)

Texas Ranger (wood engraving 1848)

The Texas Rangers were the most notorious of the volunteer units.  According to Brown, “The Rangers hoped either to find and eliminate the guerrillas or to terrorize the local people to such an extent that they would stop supporting the irregulars.”[66]  Commanding officers did little to control the Rangers, as their skills as scouts and guerrilla fighters were highly valued.  Indeed, Texas Ranger units were parceled out to every army division.

American journalists were on hand to observe the American occupation of Monterrey.  The Charleston Mercury reported on October 11, 1846:   “As at Matamoros, murder, robbery, and rape were committed in the broad light of day, and as if desirous to signalize themselves at Monterrey by some new act of atrocity, they burned many of the thatched huts of the poor peasants.  It is thought that one hundred of the inhabitants were murdered in cold blood, and one . . . was shot dead at noon-day in the main street of the city.”  This story was republished in other U.S. newspapers and in London as well.  American depredations were also reported in the Mexican press, which charged that “the volunteers, the most unprincipled and ungovernable class at home, have been let loose like blood-hounds on Mexico.[67]
The fall of Lt. Col. Henry Clay, Jr.

The fall of Lt. Col. Henry Clay, Jr. at the Battle of Buena Vista

With Monterrey secured, Taylor extended the American occupation to other northeastern towns and cities.  General John E. Wool, who recently arrived from San Antonio, was ordered to take charge of Parras; General Worth was directed to Saltillo; and Taylor proceeded to Victoria, 175 miles south of Monterrey.  Taylor soon had to backtrack, however, as Santa Anna had intercepted a letter revealing that half of Taylor’s army was departing to join General Scott’s impending invasion on the east coast.  Recognizing Taylor’s vulnerability, Santa Anna hastily organized a force of nearly 20,000 soldiers at San Luis Potosí.  On the punishing 250-mile hike north to Buena Vista, nearly one-fourth of his army deserted or died.  The survivors arrived hungry and exhausted. 

The two armies clashed at Buena Vista on February 22-23, 1847.  The battle was fiercely fought and produced heavy casualties, especially on the Mexican side.  After two days, Taylor’s troops were on the verge of defeat, but Santa Anna abruptly decided to withdraw his remaining forces in order to meet General Scott’s invasion into the heart of Mexico.  Despite Taylor’s near defeat, he was hailed as a hero on the home front and marked as a potential presidential candidate in 1848.
News of Buena Vista

News of Buena Vista

One week after the Battle of Buena Vista, the last formal battle in the northeast region took place outside the city of Chihuahua.  Col. Alexander W. Doniphan and some 1,000 soldiers, having made their way from Santa Fe, defeated a Mexican force of comparable size and took charge of the city.  Doniphan arranged for American merchants to be established and kept watch for guerrilla activity during his two month stay.  With many of his volunteer enlistments ending soon, he took his regiment to Saltillo on April 28, allowing the Mexican governor of the state to take charge of the city.

With the end of major battles in the northeastern region, Taylor focused on maintaining law and order, preventing and responding to guerrilla attacks, and, to a lesser degree, protecting communities from Indian attacks.  Comanche, Apache, and Navaho raids in northern Mexico were on the rise, due in part to the diversion of Mexican forces to fight the Americans.  The U.S. imposed martial law on Mexican communities.  One regulation stated, “All Mexicans, except the Police, are ordered to confine themselves to their houses after sunset. Any found in the streets after that time will be fired upon.”  Another warned that any Mexican found selling liquor “will be punished by confiscating all their property and such other punishment as may be ordered by a court martial, not excepting death.”[68] 

General John E. Wool

General Wool, as military governor of Saltillo, added to the oppression by instituting a policy that held whole towns responsible for any stolen U.S. Army goods, threatening the residents with large fines.  The innocent, as such, were made to pay for the guilty.  “Within a few months,” notes Brown, “Wool collected more than $8,000 in fines, as well as livestock and other personal property.[69]  General Wool also made an effort to crack down on reckless American violence and abuse.  He imposed stricter discipline, instituted curfews, tried to keep troops away from population centers, and threatened disobedient soldiers with discharge.  Judging by news reports, however, these measures were not enough.  John Durivage, a correspondent for the New Orleans Picayune stationed in Monterrey, wrote on April 25, 1847:

You have published accounts of the disgraceful outrage perpetrated before the battle of Buena Vista, and will be no less shocked to learn that an equally sickening scene of outrageous barbarity has been perpetrated in this region by persons calling themselves Americans.  It appears that near a little town called Guadalupe, an American was shot two or three weeks ago; and his companions and friends determined to revenge his death.  Accordingly a party of a dozen or twenty men visited the place and deliberately murdered twenty-four Mexicans.[70]

General Taylor confirmed the lawless personal violence in a dispatch to the War Department on June 16, 1847:

I deeply regret to report that many of the twelve months’ volunteers, in their route hence to the lower Rio Grande, have committed extensive depredation and outrages upon the peaceable inhabitants.  There is scarcely a form of crime that has not been reported to me as committed by them . . . Were it possible to rouse the Mexican people to resistance, no more effectual plan could be devised than the very one pursued by some of our volunteer regiments.[71]

Early photo of U.S. soldiers entering Saltillo

Early photo of U.S. soldiers entering Saltillo

President Polk’s blunt strategy for dealing with the difficulties of occupation was to win the war as quickly as possible and get out.  In public pronouncements he gave no indication of the problems of occupation.  In his Second Annual Message to Congress in December 1846, he praised “our volunteer citizen soldiers, who so promptly responded to their country’s call, with an experience of the discipline of a camp of only a few weeks, have borne their part in the hard-fought battle of Monterrey with a constancy and courage equal to that of veteran troops and worthy of the highest admiration.”  There was no mention of discipline problems or abuses, or efforts to correct these.  His message the following year was much the same.  “Too much praise can not be bestowed upon our officers and men, regulars and volunteers, for their gallantry, discipline, indomitable courage, and perseverance, all seeking the post of danger and vying with each other in deeds of noble daring.”[72]

Newspaper editors and journalists generally followed the president’s patriotic lead in reporting on the war, but there were times when, as Josiah Gregg of the Louisville Daily Journal wrote, “it is painful to feel compelled to confess that the volunteers . . . have given much cause for the dread in which they are held by the Mexican citizens.”  Citing recent “depredations [that] have been a disgrace to the American name,” he wrote to his editors, “Can you explain this?”[73]

The “Army of the West” in Nuevo México and Alta California

In 1846, there were about 7,000 Mexicans in Alta California and some 65,000 Mexicans and Pueblo Indians in Nuevo México.[74]  There were also about 2,000 Americans in Alta California, most having arrived within the last five years without regard to Mexican immigration laws.  The two territories made up a significant portion of the Mexican land mass but held only one percent of the Mexican population. In Nuevo México, Governor Manuel Armijo received news of the war in early July.  To meet the expected American invasion, he requested troops from Mexico City, 1,500 miles to the south, and issued a call for volunteers.  When no troops arrived, Armijo decided to send home some 3,000 poorly armed volunteers who had responded to his call. 
Col. Stephen Kearny

Col. Stephen Kearny

Col. Stephen Kearny’s “Army of the West” thus entered Santa Fe unopposed on August 18, 1846.  In a display of power, Kearny’s troops marched in, sabers drawn, with cannons firing in the distance, and hoisted the American flag over the governor’s palace.  Joseph Magoffin, an aide to Col. Kearny who later became mayor of El Paso, indicated in his official report that the Americans were graciously received by the inhabitants:  “Gen’l. Kearny entered this city on 18th 5 o’c P.M., the authorities & people of the place being ready to give him a hearty welcome.”[75]  Lieutenant Richard Smith Elliott, a correspondent for the St. Louis Reveille, looked more closely at the reactions of the residents:

Our march into the city . . . was extremely warlike . . . From around corners, men, with surly countenances and downcast looks regarded us with watchfulness, if not terror. . . . Strange, indeed, must have been the feelings of the citizens, when an invading army was thus entering their home . . . all the future of their destiny vague and uncertain – their new rulers strangers to their manners, language and habits, and, as they had been taught to believe, enemies to the only religion they had ever known. . . . As the American flag was raised, and the cannon boomed its glorious national salute from the hill . . . a sigh of commiseration, even for causeless distress, escaped from many a manly breast, as the wail of grief arose above the din of our horses’ tread, and reached our ears from the depth of the gloomy-looking buildings on every hand.[76]

Col. Kearny informs New Mexicans of their new status

Col. Kearny informs New Mexicans of their new status

Col. Kearny informed Governor Armijo that the United States was in possession of Santa Fe and all territory east of the upper Rio Grande, in keeping with the extended Texas border appropriated by the United States.  He addressed a gathering in the public square, imploring “the inhabitants of New Mexico to remain tranquil in their peaceable avocations and labors, with the assurance that they will not be molested by the American army, but on the contrary, they will be respected and protected in all their rights, both civil and religious.”  He warned that anyone who bore arms against the United States “will be looked upon as enemies and treated accordingly.”  Kearny also promised to “keep off the Indians” and protect “your persons and property,” a promise that undoubtedly appealed to many, as Navaho and Apache raids continued to terrorize the population outside the main cities of Santa Fe, Taos, and Albuquerque.[77]

Col. Kearny and his officers furthermore made an effort to win favor with church leaders and “reputable citizens of the city,” attending church services and holding a “splendid ball at the Palace.”  The occupation, in Magoffin’s view, was an unqualified success.  “The fact is, to make a long story short, Gen’l. Kearny by his mild & persuasive manner has induced the good people of New Mexico to believe that they now belong to the greatest nation on earth, & that the stars and stripes, which are now so gallantly waving over the capitol of this city, will always give them ample protection from foreign foes.”[78]

However exaggerated Magoffin’s account, the Indian threat did, in fact, create a measure of cooperation between the occupying American forces and New Mexicans.  On September 18, Kearny initiated a campaign against the Navajos, his forces augmented by sixty-five Mexican and Pueblo Indian volunteers.  The campaign quickly shifted to negotiations, resulting in a treaty of “permanent peace, mutual trust and friendship” on November 22.  Col. Alexander Doniphan signed the treaty on behalf of the United States.  Fourteen Navajo chiefs signed with an “X,” persuaded no doubt by the American purchase of several hundred sheep and cattle from the Navajos. Col. Kearny had meanwhile departed for California on September 25, leaving Col. Sterling Price in charge of a reduced regiment.  Before leaving, Kearny sent a report to President Polk assuring him that civil government had been established and order secured in New Mexico.  The assurance was premature. Although Kearny’s occupation was considerably less abusive than that of Taylor in the northeast region, the occupation was nevertheless unwanted and eventually resisted.  According to one account:

Bored U.S. troops, overcrowded in Santa Fe, started to attack New Mexican civilians; racial tensions escalated (in their memoirs of the conquest a number of U.S. soldiers made ugly statements expressing contempt for Mexicans).  Some New Mexicans regretted not having offered more resistance when the U.S. army took possession of the territory.  Now they planned revolts.  In December, officials uncovered a plot to overthrow the occupation forces and assassinate Governor [Charles] Bent.  The conspirators were quickly arrested, and the guard was doubled at the governor’s palace.[79]

An insurrection led by Pueblo Indians broke out in January 1847.  They killed Governor Bent, rallied support among the small towns of northern New Mexico, and prepared for an attack on Santa Fe.  Col. Price, with some 500 soldiers and artillery, attacked the rebels with maximum force at Pueblo de Taos, February 3-5.  Price reported 150 Mexican and Pueblo Indians dead, and U.S. casualties of seven dead and forty-five wounded.  Over the next three months, trials were held and 22 Mexicans and five Pueblo Indians were hanged.  William B. Drescher, a U.S. soldier who witnessed the hangings, wrote in his memoirs. “You should have seen the poor wives of the Indians hung — heard their moans and observed their despair.”[80]  The New Mexico territory thereafter remained securely in the hands of the Americans.

San Francisco harbor, 1846

The Polk administration made quick work of conquering Alta California, having prepared well in advance.  In June 1845, eleven months before the outbreak of war, he sent “secret and confidential” instructions to Commodore John Sloat, commander of U.S. naval forces in the Pacific:  “If you ascertain with certainty that Mexico has declared war against the United States, you will at once possess yourself of the port of Saint Francisco, and blockade and occupy such other ports as your force may permit.”  Sloat was thus prepared to act when he received word a year later that hostilities had commenced.  He took charge of Monterey on July 7, 1846, and San Francisco two days later, announcing, “Henceforth California will be a portion of the United States.”[81]  As in New Mexico, Sloat told the Mexican people that the U.S. was not “an enemy” but a friend who would treat them with respect.

Bear Flag revolt in northern California

Prior to Sloat’s takeover of the port cities, some thirty Americans in Sonoma, north of San Francisco, initiated a revolt on June 14, 1846.  According to an account by one of the rebels, Robert Semple, the armed group woke up General Mariano Vallejo that morning, who inquired of the raggedy looking intruders, “To what happy circumstances shall I attribute the visit of so many exalted personages?”  One rebel replied, “We mean to establish our own government in California, and independent republic, and are under arms to support it.  You are under arrest, General.”[82]  The rebels proclaimed the independent “Bear Flag Republic.”  The republic lasted only one week before John C. Frémont, an agent of Polk, arrived and took command of the rebellion in the name of the United States.  On July 15, Sloat transferred his command to Commodore Robert F. Stockton, who placed Frémont’s forces under his command.

Having secured control over the northern part of Alta California, Stockton sailed to the southern part to take the ports of Los Angeles and San Diego, which was achieved without bloodshed in August.  For the next six months, however, Mexican Californios organized resistance to the occupation.  Mexicans forced the small garrison in Los Angeles to surrender in September 1846.  When Col. Kearny’s forces arrived in San Diego in early December they were almost immediately drawn into battle against Mexican forces under Captain Andrés Pico at San Pasqual.  Kearny was forced to retreat, but one month later, a combined American force led by Commodore Stockton won the Battle of San Gabriel, ending the resistance.  Captain Pico formally surrendered Alta California on January 13, 1847, and Kearny took over as military governor. U.S. naval forces were also in control of the separate Mexican territory of Baja California, but possession was returned to Mexico in the peace treaty at the end of the war.

General Scott and the occupation of middle Mexico

General Winfield Scott was determined to prevent the unwarranted violence and discipline problems that plagued Taylor’s northeastern occupation.  It was imperative that he do so, for the population in central Mexico was much larger than that of northeastern Mexico and could cause significantly more problems.  According to an 1842 Mexican census, the population in the four Mexican states occupied by Taylor’s forces (Tamaulipas, Nuevo León, Coahuila, and Chihuahua) amounted to 424,112 people, or 6% of the total Mexican population of 7,016,300.  The population in the three states on Scott’s route to Mexico City (Veracruz, Puebla, and México) was 2,305,802, or 33% of the total Mexican population.[83]
General Scott’s army traveled 260-mile inland from Veracruz to Mexico City

General Scott’s army traveled 260-mile inland from Veracruz to Mexico City (click to enlarge)

Scott needed to win a measure of acceptance from the Mexican people in order to minimize attacks on U.S. troops, secure food and supplies en route to Mexico City, and maintain law and order in the towns and cities under U.S. control.  Upon arriving in Tampico in mid-February 1847, Scott issued General Order No. 20, or Martial Law Order, which “made rape, murder, assault, robbery, desecration of churches, disruption of religious services, and destruction of private property court-martial offenses” for all persons, Mexican and American.  According to John Brown, “All accused offenders would be tried before a court made up of officers appointed by the commanding general.  The tribunals had the authority to determine innocence or guilt and to levy punishment, which included the lash, hard labor in ball and chain, imprisonment, branding, and even death.”[84]

This edict, coupled with the fact that U.S. troops were preparing for a major military campaign rather than biding their time as an occupation force, helped curb flagrant abuses against Mexican civilians.  Yet Scott’s strategy in taking the city of Veracruz belied his expressed intention to protect civilians.  During the three-day bombardment, March 22-25, U.S. forces launched 6,700 cannonballs into the city, causing an estimated 500 civilian and military deaths and significant damage to homes, buildings, and merchandise.[85]  On the third day of the assault, Mexican General Juan Morales and the foreign consuls in the city asked for a temporary ceasefire to allow for civilians to be evacuated.  Scott rejected the request, calculating that this would only delay surrender. According to the historian Glenn Price, the bombing “was indiscriminate, with explosive shells which were lobbed up with the design of crashing through the flimsy roofs of the adobe houses and exploding among the families after falling inside.  The British press was extremely critical of this deliberate destruction of the population . . . and some American officers on the scene expressed their strong disapproval.”  Scott brushed aside the criticism, saying that his task was to take the city with the least possible loss of American lives.[86]  In this, Scott succeeded, as only fifteen U.S. soldiers were killed and fifty-five wounded.

American forces bombard Veracruz

Bombardment at Veracruz, March 25, 1847

Bombardment in Veracruz, March 25, 1847

The American press was on hand to witness the affair.  George Kendall of the New Orleans Picayune watched the American bombardment with awe.  “The conflagration was certainly the most grand I have ever witnessed,” he wrote, as fires lit up the city.  The shelling continued the next morning, which Kendall called “tremendous.”  Only later, after walking through the wreckage, did Kendall consider the lethal effects of the barrage.  The city “has been torn all to pieces – the destruction is dreadful,” he wrote.  “It is certain that women, children and non-combatants have suffered the most.”[87]  Kendall’s colleague at the New Orleans Delta, James Freaner, concurred, “The destruction of the city is most awful.  One half of it is destroyed.  Houses are blown to pieces and furniture scattered in every direction – the streets are torn up and the strongest buildings seriously damaged.”  The New York Spirit of the Times reported, “The Mexicans variously estimated their loss from 500 to 1000 killed and wounded; but all agree that the loss among the soldiery is comparatively small, and the destruction among the women and children is very great.”[88]

John Peoples of the Delta had a moment of empathy as he watched the disarmed Mexican soldiers (all paroled) shuffle out of the city, accompanied by women, children, old men, and “lame ones.”  Although Mexicans were “the enemies of every American, my heart bled for them,” he wrote.  “I could not help pitying them.”  The moment of sympathy passed quickly.  The “Stars and Stripes” were raised over the city, he wrote, and “the sound of hundreds of cannon burst upon the ear, proclaiming that the city was ours.  The bands struck up the ‘Star Spangled Banner’ and [U.S. troops marched into] the city, each regiment wearing its colors, and bands performing the choicest of our national airs.”[89]
Most Americans at home celebrated the victory at Veracruz, achieved with so few American casualties.  Scott was deemed a hero for his successful amphibious assault.  His success was due in large part to the fact that Mexico City had been in an uproar in the preceding month – the Polkos Rebellion – and could provide no additional troops to protect the city; hence, Scott’s troops landed on the beach unopposed.  For Mexicans, beyond the humiliation of defeat, there was something incongruous and hypocritical about General Scott’s order to protect Mexican civilians from undisciplined American soldiers, on the one hand, and his military tactics guaranteed to cause massive civilian casualties and property destruction, on the other.  The Mexican newspaper El Republicano, having received reports of the slaughter in Veracruz and familiar with the abuses of Taylor’s army, editorialized on April 1, 1847:  “What the United States army is coming here to do is . . . to burn our cities, loot our temples, rape our wives and daughters, kill our sons, and sacrifice our defenders right in our presence, at the doors of our homes; these scenes of death and destruction . . . will find a thousand avengers on every side.”[90]

Battle of Cerro Gordo, en route to Mexico City

As Scott’s forces regrouped and began their journey toward Mexico City, Santa Anna attempted to block Scott’s route at the strategic mountain pass of Cerro Gordo.  Santa Anna had assembled a force of 12,000 and spent a week fortifying his position.  His troops, however, were in a pitiful state, as half had marched more than 1,000 miles since the Battle of Buena Vista.  “They had suffered from hunger and heat, thirst and cold, storms and sickness, pestilence and snows,” according to Mexican authors.[91]  The battle took place on April 17-18.  The Americans planned their strategy well.  On the second day, they routed the Mexican troops and captured 3,000 soldiers and officers along with artillery, ammunition, clothing, provisions, and a chest of money.  It was a devastating defeat for Santa Anna.  He retreated to Mexico City to organize the last valiant defense.

Ten days after the Battle of Cerro Gordo, a new president of Mexico was installed, Pedro Maria Anaya.  He commissioned new Light Corps units, known as “Guerrillas of Vengeance,” and ordered them to “attack and destroy the invaders in every manner imaginable.”  By mid-May, these “irregular” units were operating all along the Veracruz-Mexico City corridor, attacking small groups of American soldiers, positioning sharpshooters along the highways, raiding supply trains, and confiscating communications.  Scott’s army, ailing from the heat and sickness, took refuge for a time in the pleasant city of Puebla, 7,000 feet above sea level and 60 miles southeast of Mexico City.  Scott reported to the War Department in July that 2,000 of his troops were too sick to fight.  Upon arriving in the Puebla, Scott issued a proclamation assuring residents that U.S. soldiers were “friends of the peaceful inhabitants of the country we occupy . . . friends of your holy religion and its priesthood.”  To reinforce his message, he instructed soldiers to salute priests on the streets, an order that riled many of his Protestant soldiers.  Scott demanded strict discipline in the town, insisting on severe punishments for those who abused Mexican civilians.  “The people,” said Scott, “must be conciliated, soothed, or well treated by every officer and man of this army, and by all its followers.”[92]

General Winfield Scott, portrait by George Catlin, c.1835

Scott was similarly intent on preventing depredations in other towns under U.S. control.  “For example,” writes the historian John C. Pinheiro, “when a mob of volunteers, regulars, and sailors robbed liquor stores, raped women, and burnt homes in a hamlet near Vera Cruz in March 1847, without a second thought Scott promptly arrested the men.”  In another case, a U.S. soldier who killed a Mexican woman at Jalapa was ordered hanged by a military tribunal.  Such enforcement signified a major improvement in curbing personal violence as compared to the American occupation in northeastern Mexico.  In April, Scott received instructions from Secretary of War Marcy to the effect that “the Army is to support itself by forced contributions levied upon the country, if at all possible.”  Like Taylor, Scott rejected this harsh option and continued to pay fair prices.[93]

The greater problem for the Americans was an expanding guerrilla war.  “The number of attacks on Americans climbed steadily during the summer and fall of 1847,” notes Brown.  Travel on the National Highway from Veracruz “became increasingly dangerous.”  Although Scott was purchasing food and other necessities from Mexican inhabitants, he was still dependent on supplies and weapons shipped to Veracruz and hauled by teamsters to Puebla.  A convoy departing Veracruz on June 4 with 138 wagons and 700 soldiers was attacked on three occasions, resulting in more than 60 casualties and some goods destroyed.  Another convoy departing in early July with 100 wagons, 700 mules, and 2,500 troops was attacked by some 1,400 irregulars, forcing the convoy to retreat to Veracruz after losing thirty men.  The convoy was reinforced and later reached Scott’s forces at Puebla.  Other American convoys departing in August and September were also attacked.  These difficulties of occupation got little attention in the United States.  Seeking heroes, the press lauded men such as Capt. Samuel Walker of the Texas Rangers, whose “bold feats struck terror to the hearts of those national high-way robbers.”[94]

Mass hanging of San Patricios as the U.S. flag appeared over Chapultepec

On August 7, 1847, Scott began his move to take the capital city.  Santa Anna had assembled a defensive force estimated at 25,000 men.  The two armies clashed just south of the city in the battles of Contreras and Churubusco, August 18-20.  American tactics and artillery, coupled with a shortage of ammunition on the part of Mexican forces, enabled the Americans to prevail once again.  The San Patricio Battalion fought with desperation, expecting to be executed if captured.  U.S. forces suffered an estimated 1,000 casualties.  They took prisoner 4,000 Mexican troops, four generals, and 85 San Patricios, of whom 50 were later executed.  The two sides signed a temporary armistice on August 23 that allowed for an exchange of prisoners and stipulated that neither side undertake military maneuvers or build fortifications.  Peace talks were initiated but quickly broke down.  General Scott accused Santa Anna of violating the truce and hostilities resumed.

The battle for Mexico City involved a series of clashes.  The first on September 8 at Molina del Rey produced heavy casualties on the American side.  On September 12, the U.S. began the bombardment of the Castle of Chapultepec, which stands atop a rocky hill overlooking the city.  On the evening of September 13, Santa Anna withdrew.  All in all, the fighting produced some 1,800 Mexican casualties, while Scott lost one quarter of his 8,000-man army.  Among the Mexican fallen were six young military cadets, ages 14-20, later commemorated as Niños Héroes.

Mexican defense at Belén Gate, Mexico City

On the morning of September 14, a delegation of city leaders approached Scott’s headquarters under a flag of truce and surrendered the city.  Scott and his army then marched into the main plaza, raised the American flag, and declared victory, but the fighting was not over, as John Eisenhower describes:

The people of Mexico City did not roll over and play dead merely because Scott entered its gates in triumph.  Quite the contrary.  Santa Anna, to be sure, had retreated to Guadalupe Hidalgo, outside town, to await developments, but the crowds in the street were not so docile. . . . they clustered around the plaza and, supposedly provoked by the “haughtiness” of the Americans, became unruly. . . . an unidentified Mexican fired a shot.  Others followed . . . The [American] units formed ranks to fire, loaded their artillery pieces with canister, and began raking the streets.  Lookouts spotted buildings from which shots had been fired.  Solid shot blasted holes in the walls and angry soldiers poured through to kill and pillage.  Since most of the civilians were fighting only with stones, resistance in any one place melted away quickly.  By noon Scott’s men held all the critical points of the city, and mob violence subsided.  Mobs roamed the streets in the unlighted city that cold night, and dead bodies littered the cobblestones. . . . The violence became sporadic, with probably more civilians killed than soldiers.[95]

The classic Mexican history of the war, Apuntes para la historia de la guerra entre México y los Estados Unidos (Notes for the history of the war between Mexico and the United States), does not refer to the Mexicans gathered as “mobs” but as patriotic citizens “acting in defense of their liberty,” even if their weapons consisted largely of “stones and billets of wood.”  The Americans responded with massive force, “bringing cannon, breaking down the doors, sacking houses, and committing a thousand other excesses. . . Horrible were the disasters that marked the occupation of Mexico. . . innocent people seized by an unbridled soldiery, attacked while disarmed, the doors of private dwellings broken, their houses sacked, and peaceful families slaughtered.”  That evening, the authors write:

The suffering families remained within their houses constantly in dread that the Americans would come to break open their homes, and perpetrate the most shameful crimes upon their persons. . . . Dead bodies lay scattered through the streets; many soldiers of the cavalry ran through the city, striking their swords against the walls, violating the doors of private houses and the stores of merchants, taking from the one the most precious goods and from the other eatables scarce among the inhabitants; for the fear of going forth to purchase them, at the very few shops open during the day, induced the quiet people to remain without food.[96]

General Scott enters Mexico City

General Scott enters Mexico City

On September 17, three days after formal surrender of the city, Scott reissued his Martial Law Order, intended to prevent extrajudicial killings and atrocities, but it was less effective in Mexico City than in Veracruz.  “Volunteers, drunk on stolen liquor, committed rape and murdered unarmed civilians,” writes Amy Greenberg, “and soldiers were in turn murdered on a daily basis.”  The personal violence of the American occupation was not immediately captured in news reports, which emphasized the great victory of U.S. forces over the larger Mexican army.  George Kendall of the New Orleans Picayune wrote, excitedly, “Another victory, glorious in its results and which has thrown additional luster upon the American arms, has been achieved today by the army under General Scott – the proud capital of Mexico has fallen into the power of a mere handful of men compared with the immense odds arrayed against them, and Santa Anna, instead of shedding his blood as he promised, is wandering with the remnant of his army no one knows whither.”[97]

It would take four and a half months before a peace treaty was signed, and another five months before both nations ratified it.  In the meantime, the guerrilla war continued against the occupying American forces; and American forces continued to expand their control over Mexico.  The war, in short, was not over.  On October 6, 1847, U.S. Secretary of War Marcy ordered Scott to “carry on further aggressive operations; to achieve new conquests; to disperse the remaining army of the enemy in your vicinity; and prevent the organization of another.”  Marcy noted that about 15,000 troops were on their way to reinforce Scott’s forces.  He demanded that Scott treat guerrillas with the “utmost severity,” and that those “who have sustained, sheltered and protected them” be treated the same.  Marcy furthermore insisted that the “burden of sustaining our forces in Mexico must be thrown, to the utmost extent, upon the people of that county . . . The men of means who have willingly contributed aid to support the Mexican army, should be forced to contribute to the support of ours.”  Scott had his officers investigate Mexican Treasury records then imposed a commensurate tax on each Mexican state.  The defeated Mexicans, as such, were made to pay for the American occupation.[98]

Death of Capt. Walker in the battle of Huamantla

Santa Anna, meanwhile, had rounded up the remnants of his army and was besieging Pueblo, attempting to cut off American supply lines.  Brig. Gen. Joseph Lane led a relief column to disperse Santa Anna’s forces.  A skirmish took place near the town of Huamantla on October 9, 1847, which resulted in the death of Captain Samuel Walker of the Texas Rangers.  Lane then ordered his men to “avenge the death of the gallant Walker,” according to a report by Lt. William D. Wilkins.  The American troops pillaged liquor stores, got drunk, and committed numerous atrocities.  According to the historian John Brown, “Lane’s troops murdered dozens of Mexicans, raped scores of women, and burned many homes.  For the only time, Scott’s troops lost all control.”  No one was punished, as Scott needed every soldier to keep the guerrilla war in check.[99]  As for the mercurial Santa Anna, he was ordered to appear before a Mexican military court of inquiry, but abandoned his command instead and headed for the Guatemalan border.  It would be five years before he returned to power.

In occupied Mexico City, Americans established two bilingual newspapers, the Daily American Star and the North American, to share news and American views.  The editors of the North American hailed the free press as one “of the most promising features of occupation by los Americanos.”  The Star proclaimed, “The liberty of the press is the shield of freedom.”   Yet when Mexican newspapers complained once too often about the American occupation, General Scott had those papers shut down.  Scott’s martial law was less effective in curbing crime in the city.  John Warland of the Star commented, “Robbery seems to be the order of the day just now. . . . Many soldiers have recently deserted from our army, and have taken to robbing for a living.”[100]
The last formal battle of the war took place near Chihuahua on March 16, 1848, when American forces under Brigadier General Sterling Price attacked Mexican forces at Santa Cruz de Rosales.  Before the battle, the Mexican officer tried to convince General Price that a peace treaty had already been signed on February 2, but to no avail.  Technically, the war remained in effect until both the Mexican and American congresses ratified the peace treaty.

IV.  Debate and opposition to the war within the United States

American citizens were clearly divided over the necessity and justice of the U.S.-Mexican War.  This was evident in Congress, where Whigs challenged the Polk administration at every turn.  It was also evident in the press.  The historian Tom Reilly counted twenty newspapers that supported the war effort, more or less, fourteen that opposed to it, and two that were neutral.  The editors of the New Orleans Delta were among those that accepted the president’s claims and goals, declaring at the outset of the war, “We must revenge our slaughtered.”  Toward the end of the war, the editors called for the annexation of all of Mexico, which went beyond the president’s ambitions.  Antiwar editorials could dependably be found in Horace Greeley’s New York Tribune.  On May 12, 1846, for example, as Congress debated Polk’s war bill, Greeley wrote:  “People of the United States! Your rulers are precipitating you into a fathomless abyss of crime and calamity! . . . Awake and arrest the work of butchery ere it shall be too late to preserve your souls from the guilt of wholesale slaughter!  Hold meetings!  Speak out!  Act!”[101]

Horace Greeley, editor and Whig Party activist, 1961 commemorative stamp

Many citizens did hold meetings, speak out, and act against the war.  Yet more were initially roused by the war spirit.  That excitement, however, subsided rather quickly.  Within six months, enlistments plummeted, and by the end of the 1847, antiwar sentiment was at its height – an oddity considering the success of American military forces in central Mexico.

Those who challenged the necessity and justice of the war presented three principled arguments:  (1) the war was an act of aggression, akin to robbery, as its aim was to force Mexico to cede territory; (2) the war was unconstitutionally begun by the president, signifying a structural threat to democratic governance; and (3) the war would extend the evil institution of slavery into new territories and furthermore increase the “slave power” in Congress.  To these principled arguments were added practical arguments regarding the high cost of the war in terms of American casualties and expenses.  No doubt, many citizens had not expected the initial slug fest on the border to turn into a full-scale invasion and conquest of Mexico.  Nor had they expected the war to last so long or for so many American casualties to result.  The higher the number of casualties, the greater the public unease and the more likely that citizens would join the chorus of antiwar voices.
Those who supported the war were not necessarily for aggression.  President Polk gave all appearances of seeking a diplomatic solution with Mexico regarding the Texas border issue; and he never mentioned his desire for California and New Mexico during his election campaign or even when he introduced his war bill in Congress.  Once he had deviously prodded Mexico into attacking U.S. troops in the disputed border area, Polk could demand that Mexico transfer its northern territories to the U.S. as compensation for its egregious aggression.  “The war has not been waged with a view to conquest,” he declared in his Second Annual Message on December 8, 1846, “but, having been commenced by Mexico, it has been carried into the enemy’s country and will be vigorously prosecuted there with a view to obtain an honorable peace, and thereby secure ample indemnity for the expenses of the war, as well as to our much-injured citizens, who hold large pecuniary demands against Mexico.”  Of course, there were many war supporters who thought it perfectly legitimate for the “superior race” to take Mexico’s northern lands, but political and diplomatic finesse required President Polk to justify his actions in accordance with just war principles (which allow for self-defense but eschew aggression), however strained the evidence and arguments.

In the same address, Polk took aim at the opponents of the war, charging them with giving “aid and comfort” to the enemy:

The war has been represented as unjust and unnecessary and as one of aggression on our part upon a weak and injured enemy. Such erroneous views, though entertained by but few, have been widely and extensively circulated, not only at home, but have been spread throughout Mexico and the whole world. A more effectual means could not have been devised to encourage the enemy and protract the war than to advocate and adhere to their cause, and thus give them “aid and comfort.”[102]

President Polk himself did not engage in extreme defamation of the war critics, in part because some were from his own party, but his allies and the pro-administration press were inclined to push the matter, labeling the war critics “Mexican Whigs.”  The insinuation of treason was strongly resented by those who deemed themselves patriots of the first order.  Theodore Parker, a Boston Unitarian minister, orator, abolitionist, and social reformer, rebutted the charge of treason in a speech on February 4, 1847:

Your President tells us it is treason to talk so!  Treason, is it?  Treason to discuss a war which the government made, and which the people are made to pay for?  If it be treason to speak against the war, what was it to make the war, to ask for 50,000 men and $74,000,000 for the war?  Why, if the people cannot discuss the war they have got to fight and to pay for, who under heaven can?  Whose business is it, if it is not yours and mine?  If my country is in the wrong, and I know it, and hold my peace, then I am guilty of treason, moral treason. . . . Treason is it, to show that this war is wrong and wicked?[103]

Parker presents an interesting case among the dissenters.  He was both an expansionist and a racist, in keeping with the times.  He expected that the United States would one day “possess the whole of the continent,” in his words.  “But this may be had fairly; with no injustice to any one; by the steady advance of a superior race, with superior ideas and a better civilization; by commerce, trade, arts; by being better than Mexico, wiser, humaner, more free and manly.”  Parker was thus not opposed to continental expansion, but he differed with Polk and company over the means to this end.  Parker viewed Mexicans as “a wretched people,” but he acknowledged that Mexicans had “abolished slavery” and did not “covet the lands of their neighbors.”  However “inferior” to their northern neighbors, the Mexicans did not deserve to be invaded and robbed of their territory.[104]

Judge William Jay, president of American Peace Society, 1848-58

Judge William Jay, APS president, 1848-58

Among the organized opposition to the war was the American Peace Society (APS), a coalition of state peace societies formed in 1828.  The group included women as well as men and was primarily active in northern states.  The group was not pacifist, but viewed war as an outdated institution and called for a “Congress of Nations,” an idea that later came to fruition in the League of Nations and United Nations.  William Jay, a New York jurist who became president of the APS in 1848, argued that “at least 23 different international controversies (including a recent Anglo-American quarrel over Maine’s boundary) had been submitted successfully to arbitration in the generation before 1840,” according to the historian Charles DeBenedetti.  APS members petitioned the Polk administration to recall American troops from Mexico and to resolve outstanding issues through mediation and negotiation.  The APS publication, Advocate of Peace, printed speeches, petitions, sermons, and poems against the war along with “eyewitness accounts of the degradation of army life and the horrors of battle.”[105]  Jay and others argued that, while immoral personal conduct was difficult to control in any war, it was all the more likely in a war whose goals were unjust and inhumane.  How could the U.S. Army prevent its soldiers from committing abuses when the whole point of the war was to rob Mexico at the point of a gun?

Criticism of American aggression and the unconstitutional origins of the war was voiced in all parts of the country.  Congressman Joshua Giddings of Ohio, an ardent abolitionist, declared that the true patriots must refuse to support “an aggressive, unholy, and unjust war.”  Henry Clay of Kentucky, Alexander Stephens of Georgia, and John C. Calhoun of South Carolina, all slaveholders, likewise denounced Polk’s aggressive actions.  The editors of the Charleston Mercury, a South Carolina newspaper associated with the Democrats, wrote in May 1846 that the “love of conquest among our people” is “the enemy of liberty and law. . . . Let us not cast away the priceless jewel of our freedom, for the lust of plunder and the pride of conquest.”[106]

Frederick Douglass, abolitionist orator and editor of the North Star

Antiwar arguments concerning the expansion of slavery, in contrast, were distinctly northern.  Northern abolitionists such as Frederick Douglass, William Lloyd Garrison, and former president John Quincy Adams were among the most vociferous and consistent opponents of the war.  Douglass connected the slavery issue to racism, writing in his newspaper, North Star, “Mexico seems a doomed victim to Anglo Saxon cupidity and love of domination.”[107]  Abolitionists also raised the argument that the slave South was intent on controlling the destiny of the nation, to the detriment of the free states.  This argument gained wide attention in the North, beyond abolitionist circles.  The Senate at the time was evenly divided between free and slave states.  Northerners saw evidence of a “slave power” conspiracy in the earlier actions of the Texas Republic, which converted a liberated region into slave territory and made extensive claims on Mexican lands in the hope of extending slavery to the Pacific coast.  Fear of the “slave power” prompted Rep. David Wilmot of Pennsylvania to introduce an amendment in the House on August 8, 1846, calling for a ban on slavery in any territories acquired from Mexico.  The Wilmot Proviso, as it was called, was approved in the House but failed in the Senate.  President Polk opposed the measure but refused to say how new territories should be established, thereby inviting speculation and apprehension.

In April 1847, the Massachusetts legislature passed a resolution that combined all of the main arguments against the war and called on all citizens “to join in efforts to arrest this gigantic crime”:

Resolved, That the present war with Mexico has its primary origin in the unconstitutional annexation to the United States of the foreign state of Texas while the same was still at war with Mexico; that it was unconstitutionally commenced by the order of the President, to General Taylor, to take military possession of territory in dispute between the United States and Mexico, and in the occupation of Mexico; and that it is now waged ingloriously–by a powerful nation against a weak neighbor–unnecessarily and without just cause, at immense cost of treasure and life, for the dismemberment of Mexico, and for the conquest of a portion of her territory, from which slavery has already been excluded, with the triple object of extending slavery, of strengthening the “Slave Power,” and of obtaining the control of the Free States, under the Constitution of the United States.

Resolved, That such a war of conquest, so hateful in its objects, so wanton, unjust, and unconstitutional in its origin and character, must be regarded as a war against freedom, against humanity, against justice, against the Union, against the Constitution, and against the Free States; and that a regard for the true interests and the highest honor of the country, not less than the impulses of Christian duty, should arouse all good citizens to join in efforts to arrest this gigantic crime, by withholding supplies, or other voluntary contributions, for its further prosecution; by calling for the withdrawal of our army within the established limits of the United States; and in every just way aiding the country to retreat from the disgraceful position of aggression which it now occupies towards a weak, distracted neighbor and sister republic.[108]

Henry David Thoreau

One Massachusetts resident, Henry David Thoreau, had already taken action.  In July 1846 he refused to pay his poll taxes in symbolic protest against the war, an action that landed him in jail for a night.  Two years later, he gave a lecture on “Resistance to Civil Government,” in which he argued in principle that citizens should disobey their government when it engages in evil policies or actions.  Such was the case in the Mexican War, he said, for “when a sixth of the population of a nation which has undertaken to be the refuge of liberty are slaves, and a whole country [Mexico] is unjustly overrun and conquered by a foreign army, and subjected to military law, I think that it is not too soon for honest men to rebel and revolutionize.”[109]

The Whig Party

Political leadership of the antiwar movement fell to the Whig Party.  Led by Clay, most party leaders embraced the first and second principled arguments – opposition to aggression and constitutional noncompliance – but were reluctant to press the slavery issue lest southern Whigs bolt the party.
The party was distinctly in the minority at the outset of the war, with the Democrats holding a 144-77 majority in the House and a 30-24 majority in the Senate.  This limited what the party could do to counter the president’s legislative measures.  During the debate over Polk’s war bill in May 1846, Whig representative Robert Schenck of Ohio offered an amendment to prevent “the forcible occupation” of Mexican territory and allow funds to be used solely for defensive purposes.[110]  Had it passed, further conflict would likely have been avoided; but the bill was voted down by the majority party.  Henceforth, most Whigs voted in favor of war appropriations, being cognizant that troops in the field needed supplies and being fearful that the American public would perceive them as unpatriotic, if not treasonous, if they did not.  Many recalled the demise of the Federalist Party in the aftermath of the War of 1812 and did not want the Whig Party to follow the same route.  Only a handful of “radical” Whigs refused to vote for war appropriations. 
John Quincy Adams

John Quincy Adams

Most Whigs members of Congress also praised American soldiers and officers in the field, the most prominent of whom were Whigs – Generals Zachary Taylor and Winfield Scott.  Former president John Quincy Adams was one of the exceptions.  He was about to speak to the issue when he suffered a fatal stroke on February 21, 1848.  According to the historian William Earl Weeks:

This occurred while he was rising to oppose a resolution paying tribute to officers who had served in the 1846-48 Mexican-American War. Adams reasoned that it was wrong to honor soldiers who fought for a dishonorable cause, in this case, to expand the domain of slavery as he saw it. He literally keeled over while standing for the principle that it is wrong for the nation to honor its veterans of unjust wars, that service in the military does not mean one can check one’s conscience at the door, and that as individuals we are always responsible for our actions.[111]

Whig members of Congress maintained a steady stream of criticism of the war.  Following the president’s Second Annual Message, Rep. Charles Hudson of Massachusetts spoke on December 16, 1846:  “The message, Mr. Chairman, declares ‘that the exiting war with Mexico was neither desired nor provoked by the United States; on the contrary, all honorable means were resorted to avert it!’  This declaration I pronounce an absolute untruth; and it will be the object of my remarks to sustain this position.  I believe the President, in making that declaration, has made a statement which is not supported, but is in reality contradicted, by the facts in the case.”[112]  In February 1847, Whigs united on a proposal to curb the president’s territorial ambitions and bring the war to a close.  Introduced by Representative Alexander Stephens and Senator John Berrien, both from Georgia, the proposal stated that “the war with Mexico ought not be prosecuted by this Government with any view to the dismemberment of that republic, or to the acquisition, by conquest, of any portion of her territory.”[113]  The Democrats once again voted the measure down.

Whig party leader Henry Clay

Later that year, the venerated Whig leader and elder statesman Henry Clay helped catalyze a new surge of peace activism.  Speaking to a large gathering in Lexington, Kentucky, on November 13, 1847, he denounced Polk’s aggressive war and its unconstitutional beginnings, and in the seventh of eight resolutions, resolved that the United States must not “acquire any foreign territory whatever, for the purpose of propagating Slavery, or of introducing slaves from the United States into such foreign territory.”  Clay’s public statement on this issue led future Whig leaders such as Zachary Taylor to similarly oppose the expansion of slavery, as did the Republican Party in the 1850s.  Clay also spoke of the great tragedy of war, his son’s recent death no doubt weighing on his mind:

In the sacrifice of human life, and in the waste of human treasure in its losses and in its burthens, it [war] affects both belligerent nations; and its sad effects of mangled bodies, of death, and of desolation, endure long after its thunders are hushed in peace.  War unhinges society, disturbs its peaceful and regular industry, and scatters poisonous seeds of disease and immorality which continue to germinate and diffuse their baneful influence long after it has ceased.  Dazzling by its glitter, pomp and pageantry, it begets a spirit of wild adventure and romantic enterprise, and often disqualifies those who embark in it, after their return from the bloody fields of battle, from engaging in the industrious and peaceful vocations of life.[114]

A journalist from the Milwaukee Sentinel and Gazette wrote:  “It may be that Mr. Clay has uttered the truth too boldly for popularity at the moment.  But succeeding years will increase the conviction that a truer and bolder man never stood forward to enlighten and guide his countrymen, even against their will.”[115]

Although elections are won and lost for a variety of reasons, the Whigs’ antiwar stance did not hurt them in Congressional elections held between August 2, 1846, and November 2, 1847.  The party picked up 37 seats in the House, giving it a slight majority when the 30th Congress convened in December 1847.  Abraham Lincoln introduced his “spot resolutions” that month, challenging the president to prove that the spot where Americans first fell was actually American territory.  On January 3, 1848, the Whig majority in the House pushed through a resolution, by a vote of 85 to 81, stating that “the war was unnecessarily and unconstitutionally commenced by the president.”  The resolution directed that a committee be formed to meet with President Polk in order “to advise and consult upon the best mode of terminating the existing war with Mexico in a manner honorable and just to both belligerents.”[116]  The new Whig majority was ready to end the war and also to prevent Polk from demanding additional Mexican territory (apart from California and New Mexico), which he was inclined to do.

The All of Mexico movement

In the wake of General Scott’s military victory in Mexico City, peace negotiations were delayed for four months, due mainly to another turnover in the Mexican government.  During that time, a new, more aggressive expansionist movement arose, the “All of Mexico” movement.  Editor John O’Sullivan, who coined the term “manifest destiny,” became a spokesperson for this movement to annex all of Mexico.  Writing in the Philadelphia Public Ledger in December 1847, he envisioned a U.S. takeover of the Mexican government’s legal system, revenue sources, schools, and institutions.  Beyond that, “Our Yankee young fellows and pretty señoritas will do the rest of the annexation, and Mexico will soon be Anglo-Saxonized, and prepared for the confederacy.”[117]  John C. Calhoun and many southerners could hardly stomach the idea of absorbing the mixed-race Mexicans into the United States and, hence, they joined the antiwar Whigs in denouncing this movement.  Nor was General Scott inclined toward the idea.  As he struggled to keep guerrilla attacks in check, he came to the conclusion that any attempt to permanently occupy the country was futile and foolhardy.  He furthermore opposed “mixing up that race with our own.”[118]
The “All of Mexico” movement rose and fell quickly, but it nonetheless lent support to the general idea of taking more territory from Mexico, beyond California and New Mexico, at this critical time.  The New York Sun imagined the benefits of taking over Mexican gold and silver mines, citing the Spanish Conquistadors as precedent:  “Look down into those mines of [San Luis] Potosi, Zacatecas, and Durango.  Look at the gold and silver glittering there in masses that wait for the pick of the [Anglo] saxon . . . Cortez carried away ship loads of gold from the Aztec . . . still thousands of mines groan with their golden burthen.”[119]  The New Orleans Picayune argued that the American conquest had left Mexico in such a weak state that it would likely “fall into the arms of a European dynasty” once U.S. troops withdrew; hence the U.S. should annex Mexico.[120]
Polk evinced no interest in annexing all of Mexico, but he was interested in slicing off more territory.  The idea had been discussed in June 1846, less than two months after the war began.  Treasury Secretary Robert J. Walker suggested “that the United States should demand a border with Mexico that began at the mouth of the Rio Grande, at 26 degree North latitude, and extend due west from that point straight to the Pacific,” according to the historian Scott Silverstone.[121]  This would include all or part of the Mexican states of Tamaulipas, Nuevo León, Coahuila, Chihuahua, Sonora, and Baja California.  Polk expressed his support for the idea at a cabinet meeting on June 30, writing in his diary, “As to the boundary which we should establish by a Treaty of Peace, I remarked that I preferred the 26 degree boundary North of it.”[122]
x_GallatinThe elderly sage, Albert Gallatin, was among those who countered the All-of-Mexico movement, publishing a booklet titled Peace with Mexico (1847).  Addressing the terms of the impending peace treaty, he wrote that the United States had “no right to impose terms inconsistent with justice.  It would be a shameful dereliction of principle, on the part of those who were averse to the annexation of Texas, to countenance any attempt to claim an acquisition of territory, or other advantage, on account of the success of our arms.”  Gallatin, in essence, was challenging the fundamental premise of imperialism, which was to acquire control over other lands and peoples by force and intimidation.  In lieu of empire building, Gallatin called on Americans to improve their own institutions, creating a “’Model Republic,’ to show that men are capable of governing themselves, and . . . [attaining] the highest standard of private and political virtue and morality.”[123]  In short, the United States should become a nation that others would want to follow rather than fear.

V.  The Treaty of Guadalupe Hidalgo

It would seem that with American troops occupying the Mexican capital and with Mexicans being taxed to support the occupation that Mexican leaders would make quick work of agreeing to Polk’s demands for Mexico’s northern territories so as to get rid of the armed foreigners.  The Mexican government, however, went through another change in leadership and period of confusion in late 1847.  Following the fall of the capital to the Americans, rebellions broke out in the states of Michoacán, Oaxaca, Tabasco, and Yucatán, threatening a complete breakdown of the nation.
Nicholas Trist

Nicholas Trist

The American negotiator in Mexico City, Nicholas P. Trist, waited patiently, having arrived in Veracruz on May 6 and begun negotiations in early September.  Prior to his appointment, Trist had been the Chief Clerk of the State Department, second in command to the secretary of state.  As a young man he had been tutored by Thomas Jefferson and married Jefferson’s granddaughter, Virginia.  He was fluent in Spanish, well-versed in law, and had served as the American consul in Havana, Cuba.  He thus appeared to be a good choice for negotiating a difficult treaty.  He was also, like Polk, a Democrat, a plantation slaveholder, and a speculator in land.  “But as it was,” writes Amy Greenberg, “Polk never got to know Nicholas Trist well enough to recognize two traits that Jefferson left to his son-in-law:  the conviction that he was smarter than almost everyone else, and an innate distrust of war.”  She adds:

The distrust of war was perhaps more his grandmother’s doing than Jefferson’s. . . . “I would as soon hear of your turning Highway man as to join any army, from ambitious motives,” she told him.  “War is at best a horrid calamity and those who wage war for the purpose of subjugating nations to their will are guilty of a heinous crime.”  She reminded “Dear Nicholas” that “when the hour arrives that you must quit this World let not your conscience upbraid you with having done any thing to dishonor humanity.”[124]

Trist’s conscience was, in fact, disturbed by the war.  Following the ratification of the peace treaty, Trist remarked, “Could those Mexicans have seen into my heart at that moment, they would have known that my feeling of shame as an American was far stronger than theirs could be as Mexicans.  For though it would not have done for me to say so there, that was a thing for every right minded American to be ashamed of, and I was ashamed of it, most cordially ashamed of it.”[125]

President Polk and his cabinet drew up Trist’s negotiating instructions in April 1847.  Trist was to obtain the Rio Grande border and the territories of Alta California and Nuevo México; and to request but not demand the peninsula of Baja California.  He was empowered to offer the Mexican government up to $30 million, depending on the territorial cessions.  In June, Polk discussed with his cabinet the possibility of demanding Baja California and all lands north of 26th degree north latitude, a line just above Monterrey and Saltillo, but he did not convey this to Trist.  Trist first met with Mexican commissioners on September 1 and 2, before the U.S. assault on Mexico City.  He negotiated the cession of California and New Mexico but, contrary to instructions, agreed to a boundary north of the Rio Grande, pending approval from Washington.  Both the Polk administration and the Mexican government rejected the tentative agreement.  The latter insisted on the Nueces River as the border with the United States and would only allow for northern California to be ceded to the United States.
The Polk administration recalled Trist on October 6, 1847.  Trist received the letter on November 16, but decided to disobey the president and remain in Mexico.  He wrote a 65-page response to Washington explaining the volatile political situation in Mexico and the need to seize the opportunity for a deal, or else “all chance of making a treaty at all will be lost . . . probably forever.”  The Mexican government was divided between Moderados (moderates) and Puros (staunch nationalists), with the Moderados in power under interim president José Manuel de la Peña y Peña (who also served as president from January 8 to June 3, 1848).  The Puros declared that they “preferred a thousand times the most disadvantageous horrors of the war and the disasters of the most frightful anarchy to the loss of national honor [that would be] the immediate consequences of an ignominious peace.”[126]  The Moderados countered that failure to make peace now could result in the loss of the Yucatán, then in rebellion, and perhaps other states.

“The peace treaty has been signed: Mexico has lost half its territory”

Trist, despite his lack of official credentials, negotiated an agreement with a special commission led by Don Bernardo Couto, Don Miguel Atristain, and Don Luis Gonzaga Cuevas.  The agreement essentially followed Polk’s original instructions to Trist.  The Treaty of Guadalupe Hidalgo (named for a small town near Mexico City) was signed on February 2, 1848, and sent to Washington.

President Polk was furious at Trist, writing in his diary that never in his life had he “felt so indignant.”  Polk cut off Trist’s salary and reimbursements.  Yet Polk, after weighing the options, decided to accept the treaty.  He wrote in his diary:  “If I were now to reject a Treaty made upon my own terms, as authorized in April last, with unanimous approbation of the Cabinet, the probability is that Congress would not grant either men or money to prosecute the war.  Should this be the result, the army now in Mexico would be constantly wasting and diminishing in numbers, and I might at last be compelled to withdraw them, and thus loose [lose] . . . New Mexico & Upper California, which were ceded to the U.S. by this Treaty.”[127]
Polk submitted the treaty to the Senate.  The Senate debated it for two weeks behind closed doors.  Senator Jefferson Davis of Mississippi introduced an amendment to increase the amount of territory ceded to the United States, adjusting the border at 26 degree latitude, which would have transferred all or part of the states of Tamaulipas. Nuevo León, Coahuila, and Chihuahua to the United States.  The amendment failed by a vote of 44–11.  With some adjustments to the treaty – rejecting a provision to recognize Mexican land grants – the Senate ratified it on March 10 by a vote of 38-14, with four senators not voting.[128]
Treaty of Guadalupe Hidalgo MapThe treaty established the boundary of Texas (U.S.) at the Rio Grande, transferred title of California and New Mexico to the U.S., and stipulated that the U.S. would pay Mexico $15 million and assume private American claims against Mexico for up to $3.25 million.  For the 80,000 Mexicans living in the ceded territories, the treaty promised a choice of relocating within Mexico or staying put and becoming American citizens.  Over 90% chose to stay, but their promised civil rights were not always respected in the ensuing years.[129]  Article XI promised U.S. assistance in dealing with the “savage tribes,” but this article was later revoked in the Gadsden Purchase agreement of 1854.  Finally, Article XXI of the treaty committed both nations to peacefully negotiating any future disagreements.  One could read this article as a belated moral victory for the advocates of peace, or, cynically, that Americans got what they wanted and foresaw no further need for aggression against Mexico.  The article read in part:

If unhappily any disagreement should hereafter arise between the Governments of the two republics, whether with respect to the interpretation of any stipulation in this treaty, or with respect to any other particular concerning the political or commercial relations of the two nations, the said Governments, in the name of those nations, do promise to each other that they will endeavour, in the most sincere and earnest manner, to settle the differences so arising, and to preserve the state of peace and friendship in which the two countries are now placing themselves, using, for this end, mutual representations and pacific negotiations.[130]

VI.  Legacies, lessons, and perspectives on the war

“War is a violent teacher, and brings most men’s passions to the same level as their circumstances.”[131]
Ancient Greek historian and philosopher Thucydides

Ancient Greek historian and philosopher Thucydides

These words, written over 2,400 years ago by the Athenian historian Thucydides, suggest that war negates our ability to understand and empathize with other human beings deemed the “enemy.”  Conversely, once the passions of war are doused or burn out, the recognition of the other’s human qualities and sensibilities may be restored.  This was the intent of the peace agreement, “to preserve the state of peace and friendship.”

Yet it was easier for Americans to forgive and forget than for Mexicans who had endured the American invasion and occupation.  Mexicans held Americans responsible for the war and its attendant sufferings.  As the Mexican newspaper, El Republicano, wrote on October 23, 1846:

A government … that starts a war without a legitimate motive is responsible for all its evils and horrors. The bloodshed, the grief of families, the pillaging, the destruction, the violence, the fires, and its works and its crimes….  Such is the case of the U.S. Government, for having initiated the unjust war it is waging against us today.[132]

Many U.S. citizens also believed that the war was unjust and unnecessary.  Their arguments and opposition to aggressive expansionism and slavery carried over into the next decade, helping to thwart American expansionist designs on Cuba and Nicaragua.  Thoreau’s essay on Civil Disobedience became a foundational text for later nonviolent change movements.  It had a profound effect on Mohandas Gandhi, who organized social justice campaigns in South Africa and Great Britain.  Gandhi, in turn, deeply influenced Martin Luther King, Jr., who led nonviolent civil disobedience campaigns in the American South.  King’s civil rights movement, in turn, inspired nonviolent revolutions in Eastern Europe against oppressive governments in the late 1980s.  The advocates of peace and justice furthermore helped establish “just war” and humanitarian principles in international institutions and law – via the Charter of the United Nations, Geneva Conventions of 1949, and human rights courts.

Had peace and justice advocacy been the dominant tradition in the United States, the history of U.S. foreign policy since the U.S.-Mexican War would no doubt have taken a different turn.  As it was, the spirit of “Manifest Destiny” rose again in the 1890s, prompting aggressive overseas expansionism and a war of conquest in the Philippines.  This was followed in the 20th century by interventions in Latin America under the Roosevelt Corollary doctrine which asserted the right of the U.S. to “exercise international police powers” in order to correct “chronic wrongdoing.”  During the Cold War, U.S. administrations claimed to be leading the “free world” while it aided repressive police states and sometimes overthrew democratic ones.  Looking back on the U.S.-Mexican War, a few lessons may be drawn that are still relevant today.
1.  Manipulating the United States into war.  Despite criticism of President Polk’s deceptive maneuvers designed to provoke Mexico into striking the first blow, this tactic was used again by other presidents.  William McKinley employed it in the Philippines in 1899.  U.S. soldiers continued to occupy the country after ostensibly helping Filipino guerrillas win their independence from Spain; shots were fired and the U.S. went to war against its former allies, intent on making the Philippines a U.S. colony.  Lyndon Johnson employed it in Vietnam in 1964.  U.S. naval forces were engaged in secret raids against North Vietnam when a North Vietnamese patrol boat fired back; the Johnson administration quickly pushed the Gulf of Tonkin Resolution through Congress and took the nation to war.  President George H. W. Bush also employed this tactic in Panama in 1989, arranging a series of provocative incidents so as to catalyze a fight, then sending in U.S. troops.  His son, President George W. Bush, went a step further and initiated a preemptive war against Iraq based on false allegations.  Clearly, there is something to be learned from the manner in which administrations have manipulated the United States into war.  The American people should not be so easily misled.  Skepticism and critical questioning of official rationales are the first steps to democratic accountability in foreign policymaking.
2.  The imperial presidency.  President Polk took the nation into war without a Congressional declaration of war, as required by the Constitution.  He placed U.S. troops in harm’s way, then demanded that Congress pass appropriations for U.S. troops already engaged in battle.  This ruse effectively undermined the checks and balances established in the Constitution.  Subsequent presidents further enlarged the executive power at the expense of the legislative branch.  During the Cold War, presidents undertook covert operations with little or no knowledge by members of Congress, let alone the public.  The historian Arthur Schlesinger warned of unchecked presidential powers in his book, The Imperial Presidency (1973).  Today, the executive branch has assumed the right to assassinate suspected terrorists, including American citizens, in countries with which the United States is not at war.  There is no legal recourse to contest the order to kill and no accountability for civilian casualties.[133]
3.  The fog of war rhetoric.  Henry Clay Jr. did not question the purpose of Mr. Polk’s war, according to his father, but only wanted to serve his country, compelled by a sense of national honor.  His response was not atypical among men of fighting age.  War was surrounded by notions of duty, honor, manhood, heroism, and glory, all of which dissuaded citizens from examining how Mr. Polk camouflaged his aggression in defensive rhetoric.  This difficulty was compounded by racist stereotypes, dehumanizing depictions of the “enemy,” and a self-righteous, quasi-religious ideology – “Manifest Destiny” – that presumably gave Anglo Americans the right to rule North America.  Such preconceptions enabled President Polk to manipulate the debate over war to his advantage; indeed, to cut short that debate in favor of going to war.  In future years, the challenge of piercing through the fog of war rhetoric would increase with the establishment of propaganda agencies within the government, patriotic rituals, and constant encouragement to “support our troops” irrespective of where and why they are sent abroad.
4.  Counter-insurgency warfare.  The U.S.-Mexican War was the United States’ first counter-insurgency war in a foreign country but not its last.  The U.S. military occupation of Mexico sparked a virulent guerrilla war, which in turn led to harsh U.S. responses extending to the civilian population.  Although U.S. commanders attempted to prevent personal violence against civilians, their efforts could not make up for the overall harm done by the U.S. invasion and occupation.  This lesson – that an invading force invariably creates its own resistance and can never win the “hearts and minds” of the occupied nation – seems yet unlearned.  The “benevolent assimilation” of the Filipinos led to 200,000 civilian deaths and the American war in Vietnam resulted in the death of some three million soldiers and civilians.  The U.S. military has sought to learn from these wars and, at the least, avoid civilian massacres, but the essential problem is political – the decision to invade a country.  In the case of Afghanistan (2001) and Iraq (2003), the U.S. overthrew existing regimes and has since become mired in counter-insurgency wars.  The utility of military force for creating political stability is overrated, especially when that force is imposed by a foreign nation.
5.  International prestige.  However unjust the war against Mexico, many Americans have celebrated its results as a boon to national prosperity, power, and prestige.  Mexico lost 55% of its territory to the United States between 1836 and 1848 (including Texas).  There is no doubt that this huge addition of territory benefited the American economy and increased U.S. power vis-à-vis other nations.  Yet the idea that the U.S. conquest of Mexico won the world’s respect is something of a conceit of empires.  True, the imperial powers of Europe became reluctant to antagonize the U.S., but neither France nor Great Britain found anything praiseworthy in the U.S. land grab in Mexico.  Indeed, the general perception was that the United States was an aggressive nation that abused international law whenever its self-interest demanded; not only by conducting an offensive war against Mexico (in the name of defense), but also imposing a blockade of Mexican ports when the U.S. had protested loudly against similar European blockades during the Napoleonic Wars.  In Latin America, the U.S. was more feared than respected, as Americans had clearly revealed their disregard for “weaker” nations and non-Anglo peoples.  To induce fear is not the same as winning respect.  In subsequent years, the belief that power earns respect was translated into a mandate to establish and maintain American “credibility” in international relations.  This became a major justification for the U.S. war in Vietnam as well as proxy wars in Central America during the 1980s.

Historical interpretations and perspectives

x_ApuntesThe first substantive history of the war was written by fifteen Mexican writers and intellectuals while U.S. troops were still occupying Mexico City.  Their book, Apuntes para la historia de la guerra entre México y los Estados Unidos (Notes for the history of the war between Mexico and the United States), published in 1848, captures the essence of the war for the Mexican people in the first sentence:  “To contemplate the state of degradation and ruin to which the mournful war with the United States has reduced the Republic, is painful.”  What caused the war?  “The insatiable ambition of the United States, favored by our weakness, caused the war,” say the writers.[134]  This view of the causes and effects of “La Guerra de la Intervención Norteamericana” (the War of North American Intervention) has not fundamentally changed over time in Mexico.  In the aftermath of the war, the Mexican statesman Lucas Alamán declared it the “most unjust war in history, provoked by the ambition, not of an absolute monarchy but of a republic that claims to be at the forefront of nineteenth century civilization.”[135]
In the United States, the U.S.-Mexican War has been viewed through different lenses.  In a sense, the debate between President Polk and his critics has never ended.  One year after the war ended, two histories were published that respectively reflected these contrasting views.

x_BrooksNathan Brooks, in A Complete History of the Mexican War (1849) justified the Polk administration’s actions as “defensive” and claimed that the war had the “most beneficial consequences” for both Americans and Mexicans.  The benefits for Americans included “the rapid settlement of the newly-acquired territory,” a revitalization of “manly vigour,” and “a prominent rank among the nations of the earth,” owing to the fact that the U.S. had successfully invaded a foreign country.  The 80,000 Mexicans who became Americans by virtue of the ceded territory were said to benefit by “the example of their northern neighbours, who may settle among them, . . . [and] raise them from their present ignorance and degradation, to all the blessings of rational liberty and a higher civilization.”  Even Mexico was said to benefit from the war, as “she will at length rise to an appreciation of real liberty, learn that her true policy is industry and peace, and, beating her ‘swords into ploughshares, and her spears into pruning-hooks,’ find her chief wealth and happiness in peaceful, health-inspiring toil.  Nor is this all,” Brooks continued:

The light of liberty and civilization, from where our flag is now planted on the shores of the Pacific, will illumine not only the adjacent countries, but the far-off islands of the watery waste.  From the bay of San Francisco, our white- winged ships will visit the shores of Asia and Africa, and each green isle that gems the Southern Ocean, freighted for their heathen inhabitants not merely with perishable merchandise, but the ‘true riches,’ civilization, and the knowledge of the one God, causing the ‘isles to be glad,’ and the ‘desert to smile and blossom as the rose.’ [136]

x_JayWilliam Jay, son of famous diplomat John Jay, a jurist, and a peace advocate, provided a counterpoint to Brooks’ celebratory history in A Review of the Causes and Consequences of the Mexican War (1849).  Jay challenged the idea that Americans are somehow exceptional, writing that “American soldiers are like other soldiers,” being subject to the same tendency toward cruelty and brutality as other fighting men.  He made this point again and again by quoting dozens of newspaper stories describing or alluding to atrocities committed by American troops during the war.  These newspaper entries, placed in sequence and corroborated by official reports, produce a sobering effect on the reader.  Jay’s purpose in writing the book, as he explained in the Introduction, was to “enforce the duty of preserving Peace, by exhibiting the wickedness, the baseness, and the calamitous consequences of a victorious War.”  The “admiration of military prowess,” he furthermore warned, “is corrupting the morals and jeopardizing the liberties of the Republic.”[137]
Most Americans did not agree with Jay’s last point.  The citizenry elected two generals in subsequent presidential elections, Major-General Zachary Taylor in 1848, and Brigadier General Franklin Pierce in 1852.  The exaltation of military “heroes” along with public rituals honoring the war dead tended to dilute strong criticism of the war in popular culture.  This tendency was reinforced by a host of personal memoirs by American soldiers published after the war, although most were not expressly political.  A number of critical histories of the war were also written over the years; in addition to Jay’s study, Albert Gallatin’s Peace with Mexico (1847), Charles T. Porter’s Review of the Mexican War (1849), Abiel Abbott Livermore’s The War with Mexico Reviewed (1850), Hermann Von Holst’s The Constitutional and Political History of the United States (1876-1892), Hubert Howe Bancroft’s History of Mexico(1883-1888), James Schouler’s History of the United States (1880-1889), and James Ford Rhodes’ History of the United States from the Compromise of 1850 (1893-1906).  Bancroft, in his six-volume study of Mexican history, described the war as “a deliberately calculated scheme of robbery” on the part of the United States.  Rhodes wrote that Polk was “deservedly unpopular” because of “a deep-seated conviction that the war had been unjustly begun.”  Schouler concluded that Polk’s strategy was to “provoke this feeble sister republic to hostilities, at the same time putting on her the offence of shedding the first blood . . . This was the program:  to let loose the demon of war, and under the smoke of defending the fourth part of Mexico we had just snatched from her [Texas] to despoil her of another [California].”[138]
x-Smith-1 - Copy (2)Renewed controversy over interpretations of the U.S.-Mexican War emerged in the wake of two U.S. military interventions in Mexico (1914 and 1916) and U.S. entry into World War I (1917-1918) – a time when historians were recruited to promote the war effort.  The need to legitimize U.S. interventions in Mexico, Central America, and the Caribbean demanded that the past U.S.-Mexican War be re-examined and justified.  The most lauded of these justifications was Justin H. Smith’s two-volume study, The War with Mexico (1919).  Discounting previous studies, Smith laid full blame for the war on Mexico.  “Mexico wanted it; Mexico threatened it; Mexico issued orders to wage it,” he wrote.  Smith described American soldiers as “brave and honest men who love the truth,” while characterizing Mexicans as “difficult” people beholden to despots who were “unable to fathom our [American] goodwill, sincerity, patriotism, resoluteness, and courage.”  He regarded Polk’s opponents as “virtual enemies of the country.”  In explaining why so many historians had arrived at conclusions contrary to his own, Smith dismissed their interpretations as “resting largely upon traditional prejudices and misinformation,” whereas his were “resting on facts.”[139]
Smith’s blatantly nationalistic view put critics of the war on the defensive, but criticism nonetheless continued, for example, in Richard Stenberg’s essays during the 1930s.  As relations between the U.S. and Mexico warmed under Franklin Roosevelt’s Good Neighbor Policy and the World War II alliance, an educational survey in 1944 “found new sympathy for Mexico in American textbooks.”  The American Council on Education’s Committee on the Study of Teaching Materials on Inter-American Subjects concluded in its report:  “It is very probably that the student who reads any of these accounts [in American textbooks] . . . would be led to take a critical view of the American position and to acquire a tolerance, if not complete approval, of Mexican acts.”[140]
During the Vietnam War era, two American authors took aim at Smith’s earlier study.  Glenn Price, in Origins of the War with Mexico: The Polk-Stockton Intrigue (1967), described Smith’s study as “one of the most flagrantly biased works in American history.”  Smith’s discussion of the origins of the war, in particular, “was simply preposterous as history; it was an extraordinary case of special pleading which suggested what was false and attempted to suppress what was true.”   Gene Brack, in Mexico Views Manifest Destiny, 1821-1846 (1975), integrated Mexican views and documents into his narrative, providing a more balanced international perspective on the war.  Brack dedicated the last eleven pages of his book to countering Justin Smith’s claims and assumptions about Mexico and the war, describing Smith’s study as an “outrageously ethnocentric account of the war.”  Another study of note during this time was John Schroeder’s Mr. Polk’s War: American Opposition and Dissent, 1846-1848 (1973), which focused mainly on the Whig Party’s opposition to the war.[141]

x_PletcherIn the view of many historians, the successor to Smith’s voluminous study was David Pletcher’s heavily footnoted work, The Diplomacy of Annexation: Texas, Oregon, and the Mexican War (1973).  Pletcher evaluated President Polk’s foreign policies on the basis of whether they served American national interests.  He thus continued Smith’s nationalistic framing of the war but, unlike Smith, was hesitant to embrace Polk’s course of action and was more respectful of contrary views.  Pletcher drew up a balance sheet of U.S. gains and losses.  The gains were primarily the acquisition of “more than 1,200,000 square miles of territory” and “the increasing respect of Europeans” presumably impressed by America’s “show of power.”

Against these American gains of territory and prestige, however, the appraising historian must charge certain losses.  Some of these were the familiar costs of all wars: about 12,800 men dead out of 90,000 under arms and about $100 million in expenses, to which might be added the $15 million paid to Mexico under the peace treaty.  The families and friends of the dead soldiers were the chief sufferers, for the growing nation hardly felt the expenditure of men and money.

There were intangible deficits as well.  One was the reaction in Latin America to the nation’s “overblown chauvinism with strong hints of militarism and racism,” leading to a negative “stereotype” of the U.S. as “the Colossus of the North.”  The most “alarming” result, however, was the widening division in the U.S. over whether the new territories should be free or slave.  All in all, Pletcher gives the impression that the benefits outweigh the deficits, but he allows for the possibility that “later generations might reasonably complain that he [Polk] served his country ill by paying an unnecessarily high price in money, in lives, and in national disunity.”  In fact, past generations came to this conclusion, beginning with Mr. Polk’s many critics.  In his concluding chapter, Pletcher asked the question, “Was the war, in fact, necessary?”  His exploration of this question, however, is confined to the framework of what’s good for the United States; hence, the choice comes down to whether the U.S. should obtain Mexican territories quickly by force or more slowly by population infiltration and subversion.[142]

Historian Josefina Zoraida Vázquez

Historian Josefina Zoraida Vázquez

Mexican historian Josefina Zoraida Vázquez found much to criticize in a scholarly review of Pletcher’s study.  While praising Pletcher’s grasp of international diplomacy, she cited a lack of understanding and inclusion of Mexican experiences and perspectives as well as crude stereotypes.  Vazquez took issue with Pletcher’s summary judgment that Mexico was in a state of “confusion, mismanagement and humiliation” in the early 1840s, arguing that Pletcher failed to identify the experiences and conditions that gave rise to Mexico’s troubles, including three international wars.  Regarding Polk’s territorial ambitions, Vazquez found Pletcher’s analysis to be almost a cover-up, arguing that Pletcher exonerated Polk of any conspiracy or provocation, and took at face value Polk’s claim that his aggressive actions were designed merely to allow the U.S. to negotiate from a position of strength.[143]

x_EisenhowerTaking stock of the long train of historical writing on the U.S.-Mexican War, the American military historian John Eisenhower, son of President Dwight D. Eisenhower, wrote in So Far from God: The U.S. War with Mexico, 1846-1848 (1989), “without a doubt, the preponderance of American opinion has agreed with [Ulysses S.] Grant that the United States treated Mexico unjustly.”  Indeed, Grant’s view of the war was incorporated into the title of Amy S. Greenberg’s engaging study, A Wicked War: Polk, Clay, Lincoln, and the 1846 U.S. Invasion of Mexico (2012).  Yet Eisenhower also indicated that “excessive” remorse is not necessary, since, in his view, if the United States had not taken Mexico’s northern territories, some other power “would inevitably” have done so, given Mexico’s military weakness and political instability:

To the student of today the fate of Mexico is sad, for the Mexicans were victims of both their history and U.S. expansionism.  But that sadness need not be exacerbated by excessive shame for the conduct of the United States, because Mexico’s disorganization, corruption, and weakness created a power vacuum that would inevitably have been filled by some predator – if not the United States, then Britain, less likely France, and even, remotely, Russia.  American haste to occupy California, for example, was prompted more by fear of British action than by concern of what Mexico would do.  After all, the United States and Britain were threatening war over the Oregon territory just north of California.  Mexico’s weakness stemmed from nearly three centuries of autocratic Spanish rule and from its own devastating war of independence, not from the actions of the United States.[144]

x_Greenberg_Eisenhower’s claim of “inevitability” is actually counterfactual conjecture.  No one can know what would have happened had the Polk administration not pursued a war against Mexico.  He also overstates British designs on California as justification for U.S. aggression.  Eisenhower’s central argument should nevertheless be considered:  does the weakness of a nation justify its conquest by a more powerful nation?  If so, Americans have nothing to regret for taking half of Mexico in the 1840s; nor for that matter, in expropriating Native American lands across North America.  If one legitimizes the use of force on the basis of weakness of countervailing forces, then it may also be argued that the imperial nations of Europe had every “right” to conquer, colonize, enslave, and exploit the rest of the world for 500 years.  This logic would similarly justify Imperial Japan’s rampage across Asia and Adolf Hitler’s quest for lebensraum during World War II – had the Axis powers won.  Where does it end?  Eisenhower counsels against “excessive shame for the conduct of the United States,” but some measure of remorse, some sense of tragedy, is necessary in order to construct new policies in line with humanistic norms.
Twenty-four hundred years ago, the Greek historian Thucydides described a conversation between emissaries of the city-state of Athens and leaders of the island of Melos.  The Athenians wanted the Melians to submit to their imperial league and pay tribute, but the Melians wanted to remain independent, arguing that they posed no threat to Athens as a neutral state.  The Athenians countered that if they accepted Melos’ neutrality, they would look weak in the eyes of rival states.  The Athenians furthermore implored the Melians to accept the fact that “the strong do what they can, and the weak suffer what they must.”  The Melians chose to fight the superior Athenian force and, indeed, suffered the consequences.  The Athenians prevailed, killing all the adult men and selling the women and children into slavery.[145]  That outcome today seems excessively brutal, but it reflects the operative principle that the strong have the right to impose their will upon the weak.
In sorting through this philosophical problem of historical justification, it is helpful to consider our collective moral evolution.  Five hundred years ago, conquest, land-grabbing, enslavement, and exploitation were common practices of the most “advanced” nations and empires of the world.  Today, slavery has been banned, formal imperialism has dissipated, national aggression has been declared illegal under international law, and human rights principles are making headway in national and international legal systems and social consciousness.  This moral progress is a result of both ethical reflection and active struggles for reform.  During the 19th century, the greatest reform was the abolition of slavery.  Mexico banned it in 1829; Great Britain outlawed it across its empire in 1834; France did the same in 1848; and movements and parties emerged in the U.S. during the 1830s and 1840s dedicated to stopping the spread of slavery or abolishing it altogether.
Moral progress in international relations was less apparent but not absent.  The main story of the day, as in the past, was empire-building and Great Power domination.  While the U.S. strove to build a national empire across North America, to the detriment of Native Americans and Mexicans, the British expanded their colonial empire across the world, to the detriment of many.  Great Britain fought a war of conquest in Afghanistan (the Afghans won), then a war to allow the sale of Afghan opium in China (the British won), and intentionally destroyed India’s textile industry in order to gain a trade monopoly.  Closer to home, the British government stood by idly while its Irish colony suffered a devastating Potato Blight (1845 to 1852) that resulted in massive starvation, disease, and emigration.  The British could nonetheless claim some measure of humanitarian progress in enforcing a ban on the Atlantic slave trade, a role that Britons remember with pride today.
Another bit of progress in the international arena can be seen in the peaceful relationship that developed between the United States and Great Britain following the War of 1812.  The two nations settled boundary disputes regarding Maine and Minnesota via the Webster-Ashburton Treaty of August 1842, and successfully negotiated competing claims in Oregon territory in June 1846.  These choices were not fated.  Fighting had broken out in the Maine-New Brunswick area in February 1839.  A local Maine militia attacked a group of British Canadian loggers along the Aroostook River.  The Canadians counterattacked and took fifty Americans prisoner.  Massachusetts, which controlled Maine at the time, appealed to Congress for troops and money for war, but President Martin Van Buren wisely moved to douse the flames of war.[146]  He sent General Winfield Scott to patrol the border and restrain vigilante violence.  Van Buren could easily have claimed that “American blood has been shed on American soil,” then initiated a war to gain more territory, but he chose instead to use the U.S. military to maintain peace while commencing negotiations.  This was moral progress, choosing to resolve international controversies without recourse to violence.
The idea that principles of justice and humanity should be practiced in international relations was not foreign to those who lived in the 1840s.  Critics of the U.S.-Mexican War voiced such principles and even President Polk appealed to them in justifying his actions.  The fact that the critics of the U.S.-Mexican War were in the minority should not cloud our historical evaluation of their importance.  Abolitionists were also in the minority in the 1840s and yet today we hold their views to be correct and in the vanguard of progress in their time.  Critics of the U.S.-Mexican War arguably deserve this same status.  Their sustained challenge to the legitimacy of the war has become part of a rich counter-narrative to the nationalistic framing of U.S. foreign policy and lent support to the idea that all wars and proposals for wars should be assessed in accordance with just war and humanitarian principles.

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[1] Arturo Gallardo, “Mexico marks anniversary of 1847 battle with U.S.,” MySanAntonio (Associated Press), September 14, 2010,; and James M. McPherson, “America’s ‘Wicked War’,” The New York Review of Books, February 7, 2013,
[2] President James K. Polk, “Third Annual Message, December 7, 1847,” The American Presidency Project,
[3] Amy S. Greenberg, A Wicked War: Polk, Clay, Lincoln, and the 1846 U.S. Invasion of Mexico (New York: Vintage Books, 2012), p. 106; and “Abraham Lincoln Speech: The War with Mexico (January 12, 1848),”
[4] Greenberg, A Wicked War, p. 274; and Ulysses Simpson Grant, Personal Memoirs of U.S. Grant (New York: Dover Publications, Inc., 1995; orig. pub. 1885), p. 16.
[5] “Speech on His Resolution in Reference to the War with Mexico,” in H. Lee Cheek, Jr., John C. Calhoun: Selected Writings and Speeches (Washington, DC: Regnery Publishing, 2003), p. 642.
[6] “Speech of Henry Clay, at the Lexington mass meeting, 13th November, 1847: together with the resolutions adopted on that occasion,”; and Greenberg, p. 163.
[7] George C. Herring, From Colony to Superpower: U.S. Foreign Relations since 1776 (New York: Oxford University Press, 2008), pp. 199-200.
[8] “Mexico after Independence,” Mexican Embassy in the United States,
[9] Brian DeLay, War of a Thousand Deserts: Indian Raids and the U.S.-Mexican War (New Haven: Yale University Press, 2008), pp. 194, 197, 132.
[10] William Earl Weeks, Dimensions of the Early American Empire, 1754–1865, Vol. 1 of The New Cambridge History of American Foreign Relations (New York: Cambridge University Press, 2015), p. 166.
[11] Jesús Velasco-Márquez, “A Mexican Viewpoint on the War with the United States,” U.S-Mexican War, 1846-1848, Public Broadcasting Station,
[12] DeLay, pp. 179, 175.
[13] “Letters of Messrs. Clay, Benton, and Barrow, on the subject of the annexation of Texas to the United States,”
[14] DeLay, p. 220.  DeLay’s reference to the Civil War incorporates the idea that the acquisition of new territories by the United States played a large role in increasing tensions between free and slave states during the 1850s.
[15] José Joaquin de Herrera, “Proclamation” (June 4, 1845),
[16] Gene M. Brack, Mexico views manifest destiny, 1821-1846: An essay on the origins of the Mexican War (Albuquerque: University of New Mexico Press, 1975), pp. 160, 165.
[17] Weeks, p. 173.
[18] Ibid., p. 181.
[19] James Knox Polk, The Diary of James K. Polk during his Presidency, 1845 to 1849, Vol. 1 (Chicago: A. C. McClurg & Co., 1910), p. 379.
[20] Glenn W. Price, Origins of the War with Mexico: The Polk-Stockton Intrigue (Austin: University of Texas Press, 1967), p. 153.
[21] Brack, pp. 117, 148.
[22] Ulysses S. Grant, Memoirs and Selected Letters (New York: Library of America, 1990), p. 50; and Greenberg, A Wicked War, pp. 99-100.  Col. Hitchcock also wrote in his diary, while camping near the Rio Grande on March 26, 1846, “It looks as if the government sent a small force on purpose to bring on a war, so as to have a pretext for taking California and as much of this country as it chooses; for, whatever becomes of this army, there is no doubt of a war between the United States and Mexico.”  Ethan Allen Hitchcock, Fifty Years in Camp and Field: Diary of Major-General Ethan Allen Hitchcock, U.S. A., ed. William Augustus Croffut (New York Putnam’s Sons, 1909), 12-13; cited in David Vine, The United States of War: A Global History of America’s Endless Conflicts, from Columbus to the Islamic State (Oakland: University of California Press, 2020), 85.  
[23] Weeks, p. 185.
[24] “Biographical sketch of Hon. Linn Boyd, of Kentucky, the present speaker of the House of representatives of the United States,”
[25] Robert Selph Henry, The Story of the Mexican War (Boston: Da Capo Press, 1989; orig. pub. 1950), p. 240; and Ernest McPherson Lander, Jr., Reluctant Imperialists: Calhoun, the South Carolinians, and the Mexican War (Baton Rouge: Louisiana State University Press, 1980), p. 7.
[26] John H. Schroeder, Mr. Polk’s War: American Opposition and Dissent, 1846-1848 (Madison: University of Wisconsin Press, 1973), p. 31; and “Representative Joshua Giddings Calls the Mexican War ‘Unjust,’ 1846,” in Ballard C. Campbell, Issues and Controversies in American History: American Wars (New York: Infobase Learning, 2012), p. 96.
[27] Abridgement of the Debates of Congress, from 1789 to 1856, Vol. XV (New York: D. Appleton & Company, 1861), pp. 494-95.
[28] Schroeder, p. 13.
[29] Campbell, p. 85.
[30] David M. Pletcher, The Diplomacy of Annexation: Texas, Oregon, and the Mexican War (Columbia: University of Missouri Press, 1973), pp. 445-49.
[31] “Walt Whitman on the Mexican War and Annexation of Territory, 1846,” May 11, 1846,
[32] Herring, p. 98.
[33] Tom Reilly, War with Mexico! America’s Reporters Cover the Battlefront (Lawrence: University of Kansas Press, 2010), p. 218.
[34] Price, p. 17.
[35] Greenberg, pp. 95-96.
[36] “Andrew Jackson’s Speech to Congress on Indian Removal,” December 6, 1830,; and Reginald Horsman, Race and Manifest Destiny: The Origins of American Racial Anglo-Saxonism (Cambridge, Mass.: Harvard University Press, 1981), p. 235.
[37] Brack, pp. 99. 122.  Racist attitudes were also behind an 1844 ordinance that ordered all black people out of Oregon Country, an expansive territory under American rule that stretched from the Pacific coast to the Rocky Mountains.  The provisional government enacted a law declaring that those who refused to leave would be severely whipped by “not less than twenty or more than thirty-nine stripes,” to be repeated every six months until they left.  See DeNeen L. Brown, “When Portland banned blacks: Oregon’s shameful history as an ‘all-white’ state,” Washington Post, June 17, 2017,
[38] John S. D. Eisenhower, So Far from God: The U.S. War with Mexico, 1846-1848 (New York: Random House, 1989), p. xix.
[39] “John L. O’Sullivan on Manifest Destiny, 1839,” excerpted from “The Great Nation of Futurity,” The United States Democratic Review, Volume 6, Issue 23, pp. 426-430,
[40] Herring, p. 194.
[41] President James K. Polk, “Third Annual Message, December 7, 1847,” The American Presidency Project,
[42] Letter from Albert Gallatin to Garret Davis, February 16, 1848, in Henry Adams, ed., The Writings of Albert Gallatin, Vol., 2 (Philadelphia: J. B. Lippincott & Co., 1879).
[43] American Peace Society Records, 1838-1947, Swarthmore College Peace Collection, DG OO3, Abstract; and Horsman, p. 271.
[44] Reilly, p. 9.
[45] Ibid., p. 71.
[46] Reilly, pp. 71, 42; and Michael Scott Van Wagenen, Remembering the Forgotten War: The Enduring Legacies of the U.S.-Mexican War (Amherst: University of Massachusetts Press, 2012), p. 22.
[47] Paul Foos, A Short, Offhand, Killing Affair: Soldiers and Social Conflict during the Mexican-American War (Chapel Hill: University of North Carolina Press, 2002), pp. 17, 23; Greenberg, pp. 139-40; and Robert E. May, “Invisible Men: Blacks and the U.S. Army in the Mexican War,” The Historian, Vol. 49, Issue 4 (August 1987), p. 465.
[48] Foos, p. 13.
[49] Greenberg, p. 131.
[50] Eisenhower, p. xviii. Justin H. Smith, in his two-volume study, The War with Mexico (1919), counts 58,812 volunteers, and 31,024 regulars that served in Mexico.  Eisenhower includes in his calculations volunteers who did not serve in Mexico.  He writes, “Of the 104,556 men who served in the army, both regulars and volunteers, 13,768 men died, the highest death rate of any war in our history.”  See also, “The U.S.-Mexican War: Some Statistics,”
[51] Casualty figures from Derek R. Mallett, “Casualties Mexico” and “Casualties United States,” in Spencer C. Tucker, editor, The Encyclopedia of the Mexican-American War: A Political, Social, and Military History, Volume One, A-L, p. 126. Figures for participation and death rate of U.S. soldier participation are taken from Justin Smith’s study.
[52] Mallett, p. 125.
[53] Foos, pp. 17-18.
[54] Walter Nugent, Habits of Empire: A History of American Expansion (New York: Vintage Books, 2009), p. 205.
[55] Foos, p. 102; and Lander, p. 54.
[56] Reilly, p. 152.
[57] Paul Joseph Springer, “American Prisoner of War Policy and Practice from the Revolutionary War to the War on Terror” (dissertation, Texas A&M University, May 2006), pp. 94-95,
[58] Brigadier General John S. Brown, “The U.S. Army Campaigns of the Mexican War: The Occupation of Mexico, May 1846 – July 1848,” Center of Military History, United States Army, 2006, p. 17,
[59] Eisenhower, p. 100; and Greenberg, p. 131.
[60] Reilly, pp. 39, 47, 56.
[61] Greenberg, 120.
[62] Eisenhower, p. 110.
[63] Ibid., 149.
[64] Polk, “Third Annual Message”; and Carol and Thomas Christensen, The U.S.-Mexican War (San Francisco: Bay Books, 1998), p. 145.
[65] Christensen, p. 145; and Greenberg, p. 132.
[66] Brown, pp. 19-21.
[67] Greenberg, p. 132.
[68] “In resuming the command of Saltillo, the commanding officer deems it proper to issue the following orders,” Feb. 27, 1847, A Continent Divided: The U.S.-Mexico War website,
[69] Brown, p. 24.
[70] William Jay, A Review of the Causes and Consequences of the Mexican War (Boston: B. B. Mussey & Co., 1849), p. 230, Internet Archive,
[71] John C. Pinheiro, Manifest Ambition: James K. Polk and Civil-Military Relations during the Mexican War (Westport, Conn.: Praeger Security International, 2007), p. 95.
[72] James K. Polk: “Second Annual Message,” December 8, 1846, The American Presidency Project,; and Polk, “Third Annual Message.”
[73] Reilly, p. 157.
[74] DeLay, p. 288.
[75] William A. Keleher, Turmoil in New Mexico, 1846-1868, (Santa Fe: Estate of William A. Keleher, 2008; facsimile of 1952 edition), p. 19.
[76] Mark L. Gardner and Marc Simmons, The Mexican War Correspondence of Richard Smith Eliot (Norman: University of Oklahoma Press, 1997), pp. 74-76.
[77] Keleher, p. 7.
[78] Ibid., pp. 19-20, 25.
[79] Christensen, p. 113.
[80] J. R. Logan, “The other side of the 1847 insurrection,” The Taos News, September 29, 2013.
[81] Jay, p. 147.
[82] Christensen, p. 99; and Dale L. Walker, Bear Flag Rising: The Conquest of California, 1846 (New York: Tom Doherty Associates, 1999), p. 124.
[83] Irving W. Levinson, Wars Within War: Mexican Guerrillas, Domestic Elites, and the United States of America, 1846-1848 (Canada: Irving W. Levinson, 2005), Table 2.1, p. 18.
[84] Brown, p. 29.
[85] “U.S. Mexican War: Battles of the War,” Public Broadcasting Station,
[86] Glenn Price, “Review of Surfboats and Horse Marines: U. S. Naval Operations in the Mexican War, 1846-48 by K. Jack Bauer (Annapolis, Maryland, United States Naval Institute, 1969),” The Journal of San Diego History, Winter 1972, Vol. 18, No. 1; and Christensen, p. 174.  More broadly, the British press took a dim view of U.S. policy toward Mexico.  In August 1845, the London Times described the U.S. annexation of Texas as “one of the basest frauds and most unwarranted acts of spoliation ever perpetrated by any nation,” presumably including those of Britain.  “The Americans have already formed new and extensive designs of aggression” toward Mexican territories, warned the Economist that same month.  Quoted in Piero Gleijeses, “A Brush with Mexico,” Diplomatic History, Vol. 19, No. 2 (April 2005), 141.
[87] Reilly, pp. 102,106-08.
[88] Ibid, pp. 106-08.  Reilly, 102,106-08. The Spirit of the Times article was republished in Western Literary Messenger, Vol. X (Buffalo), Saturday, April 17, 1847.
[89] Reilly, 106-08.
[90] Christensen, p. 163.
[91] Ibid., p. 178.
[92] Brown, pp. 15, 30; and Christensen, p. 189.
[93] Pinheiro, p. 97; and Polk, “Third Annual Message.”
[94] Brown, p. 22; and “The Thunderbolt of the Rangers at the Battle of Huamantla,” Rough and Ready Almanac, circa 1848, A Continent Divided: The U.S.-Mexico War website,
[95] Eisenhower, pp. 345-46.
[96] Ramón Alcaraz, et. al., Aputnes para la historia de la guerra entre México y los Estados Unidos (Notes for the history of the war between Mexico and the United States), 1848, pp. 377-78,
[97] Greenberg, p. 211; and Reilly, p. 178.
[98] Christensen, p. 215; and “Letter from W. L. Marcy, Secretary of War to Major General Winfield Scott, October 6, 1847,” The Executive Documents, Thirtieth Congress, First Session, Volume 7, pp. 1005-1008.
[99] Brown, p. 37.
[100] Reilly, p. 234.
[101] Ibid., pp. 55, 17, 9.
[102] James K. Polk: “Second Annual Message.”
[103] Quoted in Murray Polner and Thomas E. Woods, Jr., We Who Dared to Say No to War: American Antiwar Writing from 1812 to Now (New York: Basic Books, 2008), p. 29.
[104] Anders Stephanson, Manifest Destiny: American Expansionism and the Empire of Right (New York: Hill and Wang, 1995), p. 53.
[105] Charles DeBenedetti, The Peace Reform in American History (Bloomington: Indiana University Press, 1980), p. 47; and Howard Zinn, A People’s History of the United States (New York: HarperPerennial, 1980), p. 157.
[106] Schroeder, pp. 31, 39.
[107] Frederick Douglass, North Star, January 21, 1848, quoted in Zinn, p. 155.
[108] “The Massachusetts Legislature Condemns the War with Mexico, [April] 1847,” in Campbell, p. 98.
[109] Henry David Thoreau, On the Duty of Civil Disobedience [1849, original title: Resistance to Civil Government] (Bedford, MA: Applewood Books, 2000, pp. 11-12.
[110] The Congressional Globe: The Debates, Proceedings, and Laws, The First Session of the 29th Congress, First Session (1846), pp. 792-93.
[111] William Earl Weeks, “Nation Builder: John Quincy Adams and the Grand Strategy of the Republic,” H-Diplo Roundtable XVII, 13 (February 8, 2016),
[112] “Speech of Mr. C. Hudson, of Massachusetts, on the Portion of the President’s Message relating to the Mexican War, Delivered in the House of Reps. of the United States, Dec. 16, 1846,” page 9,
[113] Schroeder, p. 86.
[114] “Speech of Henry Clay, at the Lexington mass meeting, 13th November, 1847.”
[115] Greenberg, p. 222.
[116] Louis Fisher, “The Mexican War and Lincoln’s ‘Spot Resolutions,” Law Library of Congress, August 18, 2009, page 5,
[117] Weeks, p. 201.
[118] Greenberg, p. 222.
[119] New York Sun, October 23, 1847, quoted in Pletcher, p. 523.
[120] Sidney Lens, The Forging of the American Empire: From the Revolution to Vietnam: A History of U.S. Imperialism (Chicago: Haymarket Books, 2003; first pub. 1971), p. 132.
[121] Scott A. Silverstone, Divided Union: The Politics of War in the Early American Republic (Ithaca: Cornell University, 2004), p. 181.
[122] Polk, Diary, Vol. 1, p. 497 (June 30, 1846).
[123] Albert Gallatin, Peace with Mexico (New York: Barlett & Welford, 1847), pp. 1-2, 23.
[124] Greenberg, pp. 93-94.
[126] Christensen, pp. 215-216; and Nugent, p. 216.
[127] Polk Diary, Vol. 3, p. 345 (February 19, 1848) and 348 (February 21, 1848); and Nugent, p. 214.
[128] Pletcher, p. 563.
[129] See Leonard Pitt, The Decline of the Californios: A Social History of the Spanish-Speaking Californians, 1846-1890 (Los Angeles: University of California press, 1966); and Verónica Castillo-Muñoz, The Other California: Land, Identity, and Politics on the Mexican Borderlands (Berkeley: University of California Press, 2016).
[130] “Treaty of Guadalupe Hidalgo,” Article XXI,
[131] “Thucydides,” New World Encyclopedia,
[132] “La guerra,” El Republicano, 23 October 1846, quoted in Jesús Velasco-Márquez, “A Mexican Viewpoint on the War with the United States,”
[133] The expansion of the secret drone assassination program followed on the heels of another secret antiterrorist program in which the U.S. was called to account for its actions. In April 2013, a bipartisan Congressional panel issued a 577-page report, concluding that the U.S. had “violated its international legal obligations by engineering ‘enforced disappearances’ and secret detentions,” and conducting “brutal interrogations” that violated the international Convention Against Torture.  Scott Shane, “U.S. Practices Torture After 9/11, Nonpartisan Review Concludes,” New York Times, April 16, 2013.
[134] Ramon Alcaraz, et. al., Apuntes para la historia de la guerra entre México y los Estados Unidos (Notes for the History of the War), (Mexico City, 1848), pp. 1, 4, English translation, Internet Archive,
[135] Joseph Contreras, In the Shadow of the Giant: The Americanization of Modern Mexico (New Brunswick, NJ: Rutgers University Press, 2009), p. 67.
[136] Nathan C. Brooks, A Complete History of the Mexican War (Philadelphia: Grigg, Elliot & Co., 1849), pp. 539-40, Internet Archive,
[137] William Jay, pp. 230, 4.
[138] Brack, p. 8; and Price, Origins of the War with Mexico, pp. 96-97.
[139] Justin H. Smith, The War with Mexico, Vol. 1, (New York: Macmillan, 1919), page ix; and Price, Origins of the War with Mexico, pp. 101-102.
[140] Van Wagenen, p. 159.
[141] Price, Origins of the War with Mexico, pp. 103-104, 117; and Brack, p. 182.  See also, Piero Gleijeses, “A Brush with Mexico,” Diplomatic History, Vol. 19, No. 2 (April 2005): 223-254, which analyzes the issue of war with Mexico in the American press and the U.S. Congress from the fall of 1845 until May 11, 1846, when fighting broke out.  In fact, there was not much said about war with Mexico because President Polk never asserted the need for such or rallied the public in favor of aggressively taking Mexico’s northern territories, in contrast to the hyped up political slogan of “54-40 or fight” regarding the division of the Oregon Territory with Britain.
[142] Pletcher, pp. 576-77, 579-80, 582, 609-11. See also, David M. Pletcher, “A Hyptothetical Question: Was the U.S.-Mexican War Necessary?” Public Broadcasting Station,
[143] Josefina Zoraida Vazquez, “Review of The Diplomacy of Annexation: Texas, Oregon and the Mexican War by David M. Pletcher, Latin American Research Review, Vol. 15, No. 2 (1980), pp. 284–86.  See also, Josefina Zoraida Vázquez, ed., México al tiempo de su guerra con Estados Unidos, 1846-1848 (Mexico City: Fondo de Cultura Económica, 1998).  For other Mexican views, see Cecil Robinson, editor and translator, The View from Chapultepec: Mexican Writers on the Mexican-American War (Tucson: University of Arizona Press, 1989).
[144] Eisenhower, pp. xvii, xix-xx.
[145] Thucydides, History of the Peloponnesian War (431 B.C.),
[146] Weeks, pp. 152-53.


Image credits


ImageArtist/creatorCourtesy of
Merger of imagesErin Meisenzahl-Peace, 2016peacehistory-usfp-org
Map of U.S. and Mexico, 1824Giggette – raster graphics imageWikipedia Commons
President James K. PolkMathew B. Brady, 1849 photographLibrary of Congress
Rep. Abraham LincolnPhotograph, circa 1845-47Library of Congress
Henry ClayDaguerreotype by Marcus Aurelius Root, March 7, 1848Wikipedia Commons
Antonio López de Santa Anna1881 U.S. history textbookU.S. History Images
Interethnic conflict zones in northern Mexico, circa 1844Brian DeLayCenter for Latin American Studies, UC Berkeley
Battle at the Alamo
Texas battles mapLatin American Studies Association
Henry Clay & Theodore Frelinghuysen campaign poster, 1844Currier & Ives–Grand National Whig bannerLibrary of Congress
James K. Polk & George B. Dallas campaign poster, 1844Currier & Ives–Grand National Democratic bannerLibrary of Congress
José Joaquín Antonio de HerreraWikipedia Commons
Sarah and James PolkWikipedia Commons
Oregon Treaty divisionLatin American Studies Association
U.S. Army camp at Corpus Christi, 1846Latin American Studies Association
Mariano Paredes y ArrillagaLatin American Studies Association
Battle of Palo AltoLithograph by Jean-Baptiste Bayot, based on drawing by Carl Nebel, pub. 1851Wikipedia Commons
U.S. House of Representatives (1845)Latin American Studies Association
Rep. Joshua GiddingsWikipedia Commons
Senator John ClaytonU.S. Senate Historical Office
“Volunteers for Mexico” recruitment posterBoston recruitment office, Dec. 1846National Museum of American History
Recruitment poster, Holmes County, OhioU.S. Army poster, Millersburg, Feb. 1, 1847University of Texas at Arlington Special Collections
“Volunteers” recruitment poster, New HampshireNew Hampshire recruitment office, Feb. 2, 1847Latin American Studies Association
John O’SullivanCover of Harper’s Weekly, Nov. 1874Wikipedia Commons
Albert Gallatin1848 photographWikipedia Commons
War news from MexicoOil on canvas by Richard Caton Woodville, 1848Crystal Bridges Museum of American Art
Literate U.S. soldiersLatin American Studies Association
Casualty listCharleston Courier, June 24, 1847Wikipedia Commons
Commemorative plaque honoring San Patricio Battalion, Mexico CityPlaced at the San Jacinto Plaza in the district of San Ángel, Mexico City in 1959Wikipedia Commons
Mexican lancers and infantryIllustration published in Military Historical Documents, Mexico City, 1958Wikipedia Commons
Map of major battles in the U.S.-Mexican War Infobase LearningWikipedia Commons
Incidents and Sufferings pamphlet Boston and New YorkAmerican Antiquarian Society, Worcester, Massachusetts
Major-General Zachary Taylor1848 engravingLibrary of Congress
Town of MatamorosL. AveryLibrary of Congress
Mexican surrender at MonterreyHand-colored lithograph, 1846Library of Congress
Texas RangerWood engraving, 1848
The fall of Lt. Col. Henry Clay, Jr. at the Battle of Buena VistaEngraving by H.S. Sadd. Drawing by T.H. MattesonLibrary of Congress
“Glorious News from Gen. Taylor”The Floridian newspaper, Tallahassee, April 3, 1847 Rare newspaper collection
General John E. WoolPhotograph, circa 1861Library of Congress
U.S. soldiers entering SaltilloPhotograph,, the Mexican-American War
Col. Stephen KearnyOriginal daguerreotype, engraved by Y.B. Welch for Graham’s MagazineWikipedia Commons
Col. Kearny proclaiming New Mexico part of the U.S., in Las Vegas, New Mexico, Aug. 15, 1846EngravingWikipedia Commons
San Francisco harbor, 1846-47Drawing by William F. Swasey, pub. 1884University of Texas at Arlington Special Collections
Bear Flag revolt in northern CaliforniaT. S. Engleheart and J. McNevin, pub. 1848University of Texas at Arlington Special Collections
Major-General Winfield ScottPhotographWikipedia Commons
American forces bombard VeracruzColored lithograph by Adolphe Jean-Baptiste and Carl Nebel, pub. 1851Wikipedia Commons
Bombardment of Veracuz, March 25, 1847Color lithograph, pub. By E.B. & E.C. Kellogg, New York, 1847Library of Congress
Battle of Cerro GordoJames BaillieUniversity of Texas at Arlington Special Collections
Map of Gen. Scott’s advance to Mexico CityUniversity of Texas at Arlington Special Collections
Mass hanging of San PatriciosWatercolor by Sam Chamberlain Wikipedia Commons
Mexican defense at the Belén gate, Mexico CityPedro LehnertDeGloyer Library, Southern Methodist University
General Scott’s Entrance into Mexico CityCarl NebelUniversity of Texas at Arlington Special Collections
The death of Capt. Walker at HuamantlaR. Magee and T. W. Strong, pub. New York, November, 1847University of Texas at Arlington Special Collections
Horace Greely postage stampUS Post Office Dept., Bureau of Engraving and Printing, 1961Wikipedia Commons
Theodore ParkerPhotograph, circa 1850Wikipedia Commons
William JayPhotographWikipedia Commons
Frederick DouglassPhotograph, circa 1850Wikipedia Commons
Henry David Thoreau1854 portrait by Samuel Worcester RowseAmerican Transcendentalism Web
John Quincy AdamsLibrary of Congress
Henry Clay
Peace with Mexico pamphlet by Albert GallatinPublished by Bartlett & Welford, New YorkInternet Archive
Nicholas TristPhotograph between 1855 and 1865Library of Congress
Tiempo de, “The Conveniently Forgotten War”
Map of Mexican Cession
Statue of Greek historian ThucydidesWikipedia Commons
Historian Josefina Zoraida Vázquez

About the author

Roger Peace is a diplomatic historian, coordinator of this website, and former community college instructor. He is the author of A Call to Conscience: The Anti-Contra War Campaign (University of Massachusetts Press, 2012) and A Just and Lasting Peace: The U.S. Peace Movement from the Cold War to Desert Storm (Noble Press, 1991).  The author appreciates the contributions from Gayle Olson-Raymer (Dept. of History, Humboldt State University) and from readers Tom Clark and Anne Meisenzahl.

Cite this article:

Bibliography: Peace, Roger. “The United States-Mexican War, 1846-1848.” United States Foreign Policy History and Resource Guide website, 2016,
Endnotes or footnotes: Roger Peace, “The United States-Mexican War, 1846-1848,” United States Foreign Policy History and Resource Guide website, 2016, War.

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