Writer, philosopher, author, naturalist, and activist Henry David Thoreau called the Mexican-American War "the work of comparatively a few individuals using the standing government as their tool." He argued that "in the outset, the people would not have consented to this measure."8 Thoreau famously spent a night in a Massachusetts jail during the summer of 1846, rather than pay taxes, which he argued was tantamount to supporting an unjust war and a federal government that continued to protect slavery. Yet most Americans did support the war, and its fighting force of American soldiers was composed almost entirely of volunteers.
Nonetheless, in what came to be remembered as one of the most controversial wars in American history, a handful of critics—some outspoken, others much more subtle—emerged from a variety of backgrounds to question the veracity of events that the Polk administration claimed had forced them to wage war on the Mexicans. The critics had good cause to suspect an artificial justification for the conflict, for Polk had run on a zealously expansionist platform and had secretly tried to purchase California and the lands of the Southwest even before the conflict had ever begun. The very pretext for war was highly dubious; in March 1846, Polk had mobilized American forces along the Rio Grande in order to provoke a reaction from Mexico, which claimed the Nueces River (not the Rio Grande) as its northern boundary—meaning that, to Mexican eyes, the Americans' patrols between the Nueces and the Rio Grande had violated Mexico's borders. Sure enough, Mexican President Mariano Paredes issued a manifesto on April 23, arguing that by advancing into Mexican territory—and simultaneously threatening Upper California with naval mobilizations off the Pacific Coast—the United States had already begun hostilities. Mexican soldiers believed it was a defensive war when they ambushed the troops of American Captain Seth B. Thornton and killed or injured about 16 of his men on April 24.
Author Herman Melville, who had not yet written the great American novel Moby-Dick, spent 1847 penning a series of satirical articles entitled "Authentic Anecdotes of Old Zach," which mocked both war hero Zachary Taylor and his supporters. Similarly, poet James Russell Lowell turned to satire in order to vent his opposition to the war through the character of fictional New England farmer Hosea Biglow. In the December 1847 edition of the Massachusetts Quarterly Review, essayist and lecturer Ralph Waldo Emerson argued that "the country needs to be extricated from its delirium at once." Jane Grey Swisshelm, a 31-year-old newspaperwoman, human rights activist, and abolitionist, decided to (in her words) "throw myself headlong into the great political maelstrom" and write against the war and slavery.
Though they constituted the minority, Whigs in Congress mounted a sustained attack on President Polk and his administration. John Quincy Adams led the first opposition vote in 1846 and called the conflict "a most unrighteous war." Even the staunch southerner and Democrat, Senator John Calhoun of South Carolina, protested against Polk's suggestion that a state of war already existed. He noted that only the legislative branch possessed the power to declare war, but he nonetheless ended up voting for the initial resolution to provide military funding. Another southerner, Whig representative Garrett Davis of Kentucky, charged Polk with blaming Mexico for a confrontation that he himself had created. In early 1848, Representative George Ashmun of Massachusetts introduced a resolution that charged the president with "unnecessarily and unconstitutionally" inciting the war. Abraham Lincoln, then a young Whig congressman from Illinois, joined 84 other Whigs in supporting that measure. Lincoln subsequently delivered a long speech in which he scrutinized President Polk's version of events that led to the war. Lincoln chided the president, saying that "Mr. Polk is too good a lawyer not to know that [the gaps in his evidence and logic are] wrong," and requested that Polk answer his challenges "with facts, and not with arguments." Although Polk's followers in the Democratic party were forced into supporting the war effort, just one year prior to the conflict Martin Van Buren had warned Polk's Secretary of the Navy, George Bancroft, that they must be careful to avoid any war in which their political enemies could charge them with the intention of waging a fight in order to extend slavery (whether the charge was true or not). Ulysses S. Grant, who was at the time a junior army officer, later reflected on the war as "one of the most unjust...ever waged by a stronger nation against a weaker nation," an act more reminiscent of "European monarchies" than a democratic republic.
Three years after his imprisonment, Thoreau went on to write "On Civil Disobedience," one of his most famous essays, based on his experience in violating what he considered to be an unjust law in order to stand up for a higher principle. In this pathbreaking work, Thoreau argued that paying his tax bill under the circumstances of the Mexican-American War and slavery amounted to "a violent and bloody measure," because it would "enable the State to commit violence and shed innocent blood." A refusal to pay taxes, on the other hand, would be a pacifist tactic that required no such violence or bloodshed. By his account, Thoreau did not pay the Massachusetts poll tax for six years, though his aunt ended up paying on his behalf to get him out of jail. Thoreau's actions and his words later served as inspiration for pacifist activists, from Mahatma Gandhi to Martin Luther King, Jr., and beyond.
Manifest Destiny was a term coined in 1845, when newspaper editor John L. O'Sullivan, a member of the radical "Locofoco" faction of the Democratic party, published it in his Democratic Review. In an article celebrating the recent Texas annexation, Sullivan wrote that "Our Manifest Destiny is to overspread the continent allotted by Providence for the free development of our yearly multiplying millions." He predicted that California would be next.
The concept of Manifest Destiny, if not the name, had been around for centuries in America; it was a vision for the future of the country, both in terms of its ultimate size, its exceptionalism, and its importance on a global scale. Thomas Jefferson had utilized a similar expression in describing his vision for the new country and the "empire for liberty" that he sought to build with the settlement of western lands after doubling the country's size with Louisiana Purchase of 1803. Jefferson envisioned a rural republic of upstanding, independent farmers and mechanics who would resist vice and corruption by dint of their virtue and self-sufficiency. Of course, for such a dream to be realized, the country would need plenty of land for its growing population.
Other proponents of expansion often derived inspiration from the Puritans, the first English settlers on the northern Atlantic coast. Massachusetts Bay Colony Governor John Winthrop told his fellow Pilgrims, who had been persecuted for their religion in England, that they must think of their settlement as "a city upon a hill," an exemplary embodiment of righteousness to the rest of the world. That metaphor would later be applied to all of America and invoked time and again, as in the 1980s when Ronald Reagan called America a "shining city upon a hill" in the global struggle against Communism. Thus Manifest Destiny has long been tied to religious notions of divine providence—the concept that God had chosen the American people to establish a new and better nation that would stretch from the Atlantic to the Pacific. In the nineteenth century, most Manifest Destiny proponents understood the "American people" to be white and Protestant, though Catholics and other immigrants could clearly benefit as well from a philosophy that encouraged territorial expansion, which might enable them to obtain land of their own.
From its very beginning, Manifest Destiny was a concept fraught with ambiguities and contradictions. It lauded America as an example to other nations, yet it proclaimed the United States an exceptional nation, specially chosen by God and populated with a superior race of people (and therefore difficult if not impossible for others to emulate). It promised land and therefore freedom and independence to its citizens, yet in order to be realized, Manifest Destiny had to deprive other people—Indians and Mexicans, most obviously—of the same assets and freedoms.
At its worst, Manifest Destiny provided a rationalization for violence, manipulation, greed, and selfishness. In his 1850 novel White Jacket, Herman Melville captured Manifest Destiny's sense of American infallibility by writing that the country bore "the ark of Liberties" for all humans, therefore actions taken in national self-interest were actually for the benefit of people everywhere. When the term "Manifest Destiny" was coined in the 1840s, hundreds of thousands of white settlers were just beginning to journey into the "Far West". There they encountered some 325,000 Indians who inhabited the Great Plains, California, the Pacific Northwest, and the Southwest; Indian populations had already declined significantly in much of the West following contact with Spanish colonizers and exposure to the diseases they carried. Notions of Anglo-Saxon racial superiority justified the displacement of not only these Indians, but also of the Mexicans. Racist ideologies led many if not most Americans to believe that Mexicans, like Indians, were cowardly and lazy, and could therefore easily be beaten. Furthermore, such ideologies reasoned, inferior races' failure to develop their lands in a productive manner—along the lines of the Protestant work ethic—meant that they deserved to lose those lands to the Americans, who would make better use of it.
Popular writers, journalists, authors, and playwrights depicted Mexicans and especially Indians as an inferior, rapidly "disappearing" people who naturally vanished before the impending takeover of their lands by white Americans. Such characterizations sought to obscure the process of bloody warfare and, sometimes, outright genocide that many whites practiced against to Mexicans and Indians. These cultural stereotypes remained intact well into the twentieth century, long after most American Indians had been confined to poor-quality land on reservations.
After the entire American mainland had been settled from coast to coast, Manifest Destiny would take on a new guise with the rise of late-nineteenth and twentieth-century American imperialism in Latin and South America, the Pacific, and beyond. Similar racial stereotypes and ideologies would be resurrected, albeit in somewhat altered forms, in regard to the people of the Philippines, Hawaii, Guam, Panama, and elsewhere.
The period of territorial expansion under President Polk, the most dramatic in the nation's history since the Louisiana Purchase of 1803 (map), coincided with the flourishing of a virulently racist sensibility among white American Protestants from both North and South. During this period, the concept of race consisted of a vague and fluctuating blend of pseudo-scientific, religious, cultural, and national elements. Though there was considerable confusion and variation among different racial theories, one matter remained paramount above all others: that no matter how one might rank the "yellow race" (Asians and Asian immigrants), the "red race" (Native Americans), the "Celtic race" (the Irish), the "brown race" (Mexicans and Latin Americans), and the black race (Africans and African Americans), whites were deemed vastly superior to all others.
Democrats argued for the Mexican-American war by utilizing racialized and gendered rhetoric to motivate and convince their constituencies that belligerent conflict was the necessary means for gaining the territory that should be American by divine right. "Inferior" races were often associated with the traits of women—the "inferior" gender—so that Mexicans, Indians, and others were portrayed as vulnerable, emasculated, and feminine as well as backwards, ignorant, and savage. Some went so far as to argue that America ought to annex all of Mexico, on the basis that Manifest Destiny would carry the national expansion across the entire hemisphere sooner or later. To instigate the conflict with Mexico, war hawks emphasized differences in religion, nationality, and race. American lust for war with Mexico was justified by plenty of anti-Catholic discourse, gendered and racialized depictions of Mexicans themselves, and the notion that Mexico was a weak, worthless, and useless country in comparison to the U.S. and that it would be better off if it was taken over by the U.S.
Yet race actually conflicted with Manifest Destiny as much as it undergirded the philosophy. This was because many race-conscious Americans who believed in pseudo-scientific theories of racial superiority worried about their country acquiring far off lands that were densely populated with "inferior" indigenous people who might then "mongrelize" the white race by intermixing with the new settlers. The United States acquired over half of Mexico's territory in the Treaty of Guadalupe Hidalgo in 1848, and the addition of most of New Mexico, California, and the disputed regions of Texas brought approximately 100,000 Mexican citizens in those regions under American control. This actually represented a disappointment for ardent expansionists like President Polk and Senator Thomas H. Benton, who proposed the annexation of all lands north and west of Laredo. This would have included all of Baja California and the northern Mexican states of Chihuahua and Sonora, with a population of some 300,000 Mexicans at the time.
The extreme racism of many Americans proved to be a key factor that prevented more of Mexico and other parts of South and Central America from being taken. The notion of Mexicans' mixed-race heritage and the threat of racial mixing between Anglo-Saxons and Hispanics was probably the most upsetting prospect of the Mexican-American War for pro-slavery politicians like South Carolinian John Calhoun, among others. Many northern Whigs were just as racist, and they did not want any territorial expansion that would increase the size and power of the slave South.
The Mexican-American War, the controversies that surrounded it, and the national debates over the land captured during it all factored directly into the coming of the American Civil War. Manifest Destiny ultimately collided with the country's greatest contradiction: The thorny problem of how to decide whether or not slavery would be allowed in the vast new territories acquired from Mexico would prove to be the undoing of the Union in 1861. Philosopher, lecturer, and intellectual Ralph Waldo Emerson proved prophetic when he wrote that America's swallowing up of over half of Mexico would be like a man who swallows arsenic, "which brings him down in turn. Mexico will poison us."