Despite the Whig victory in 1840, planters wielded considerable clout in Washington, D.C., because of the importance of cotton to the U.S. economy. In turn, Southerners needed federal support to expand into more fertile areas. The presidential election of 1844 turned on this issue, with Democratic candidate James K. Polk demanding continued expansion into Oregon and Mexico. Once Polk was in office, his claims were contested not only by Britain and Mexico but also by the Comanches, who controlled the southern plains. After the United States won vast Mexican territories in 1848, conflicts with Indians and debates over slavery only intensified.
Expanding to Oregon and Texas
Southerners eager to expand the plantation economy looked not only to the West for additional lands but also to Cuba and Nicaragua in the 1830s and 1840s. Although efforts to capture these areas failed, planters continued to press for expansion. Yet expansion was not merely a southern strategy. Northerners demanded that the United States renounce its joint occupation of the Oregon Country with Great Britain. And some northern politicians and businessmen believed that acquisition of lands in Hawaii and Samoa could benefit U.S. trade. In 1844 the Democratic Party built on these expansionist dreams to recapture the White House.
Initially, Democrats could not agree on a candidate, but they ultimately nominated a Tennessee congressman and governor, James K. Polk. The Whigs, unwilling to nominate Tyler for president, chose the well-known Kentucky senator Henry Clay. Polk ran on a platform that proclaimed the “Reoccupation of Oregon and the Annexation of Texas.” Clay, meanwhile, remained uncommitted on the issue of Texas. This proved his undoing when the small but growing Liberty Party, adamantly opposed to slavery, denounced annexation. Liberty Party candidate James G. Birney captured just enough votes in New York State to throw the state and the election to Polk.
In February 1845, a month before Polk took office, Congress passed a joint resolution annexing the Republic of Texas. The day before Polk’s inauguration, Florida was also admitted to statehood. That summer, John L. O’Sullivan, editor of the Democratic Review, captured the American mood by declaring that nothing must interfere with “the fulfillment of our manifest destiny to overspread the continent allotted by Providence for the free development of our yearly multiplying millions.” This vision of manifest destiny— of the nation’s God-given right to expand its borders—defined Polk’s presidency.
With the Florida and Texas questions seemingly resolved, President Polk turned his attention to Oregon, which stretched from the forty-second parallel to latitude 54°40' and was jointly occupied by Great Britain and the United States. Residents of either nation could settle anywhere in the region, but most of the British lived north of the Columbia River, while most Americans settled to the south.
In 1842, three years before Polk took office, settlers’ glowing reports of the mild climate and fertile soil around Puget Sound had inspired thousands of farmers and traders to migrate to Oregon. Americans flooded into the Willamette valley, and merchants involved in the China trade imagined a thriving U.S. trading post on the Oregon coast. Alarmed by this “Oregon fever,” the British tried to confine Americans to areas south of the Columbia River. But American settlers demanded access to the entire territory, proclaiming “Fifty-four forty or fight!” As president, Polk encouraged migration into Oregon, but he was unwilling to risk war with Great Britain. Instead, diplomats negotiated a treaty in 1846 that extended the border with British Canada (the forty-ninth parallel) to the Pacific Ocean. Over the next two years, Congress admitted Iowa and Wisconsin to statehood, reassuring northern residents that expansion benefited all regions of the nation.
Many of the lands newly claimed by the U.S. government were home to vast numbers of Indians. Indeed, the West had become more crowded as the U.S. government forced eastern tribes to move west of the Mississippi (see Map 10.2). When the Cherokee and other southeastern tribes were removed to Indian Territory, for example, they confronted local tribes such as the Osage. Pushed into the Southwest, the Osages came into conflict with the Comanches, who had earlier fought the Apaches for control of the southern plains. Other Indian nations were pushed onto the northern plains from the Old Northwest. There the Sioux became the dominant tribe by the 1830s after seizing hunting grounds from the Omahas, Iowas, and Cheyennes, who resettled farther south and west.
The flood of U.S. migrants into Texas and the southern plains transformed relations among Indian nations as well as with Mexico. In the face of Spanish and then Mexican claims on their lands, for example, the Comanches forged alliances with former foes like the Wichitas and the Osages. The Comanches also developed commercial ties with tribes in Indian Territory and with Mexican and Anglo-American traders on the frontiers of their respective nations. In these ways, they hoped to benefit from the imperial ambitions of the United States and Mexico while strengthening bonds among Indians in the region.
Comanche expansion was especially problematic for Mexico once it achieved independence in 1821. The young nation did not have sufficient resources to sustain the level of gift giving that Spanish authorities used to maintain peace. As a result, Comanche warriors launched continual raids against Tejano settlements in Texas. But the Comanches also developed commercial relations with residents of New Mexico, who flaunted trade regulations promulgated in Mexico City in order to maintain peace with neighboring Indians. By 1846 Comanche trade and diplomatic relations with New Mexican settlements had seriously weakened the hold of Mexican authorities on their northern provinces.
Pursuing War with Mexico
At the same time, with Texas now a state, Mexico faced growing tensions with the United States. Conflicts centered on Texas’s western border. Mexico insisted on the Nueces River as the boundary line, while Americans claimed all the land to the Rio Grande. In January 1846, Polk secretly sent emissary John Slidell to negotiate with Mexico, offering President José Herrera $30 million for New Mexico and California after securing the Rio Grande boundary. But Polk also sent U.S. troops under General Zachary Taylor across the Nueces River. Mexican officials refused to see Slidell and instead sent their own troops across the Rio Grande. Meanwhile U.S. naval commanders prepared to seize San Francisco Bay if war was declared. The Mexican government responded to these hostile overtures by sending more troops into the disputed Texas territory.
When fighting erupted near the Rio Grande in May 1846 (Map 10.3), Polk claimed that “American blood had been shed on American soil” and declared a state of war. Many Whigs in Congress protested, arguing that the president had provoked the conflict. Congressman Abraham Lincoln of Illinois demanded that Polk “show me the spot” where U.S. blood was shed. However, antiwar Whigs failed to convince the Democratic majority, and Congress voted to finance the war.
The South was solidly behind the war. As the Charleston, South Carolina, Courier declared: “Every battle fought in Mexico and every dollar spent there, but insures the acquisition of territory which must widen the field of Southern enterprise and power in the future.” Most Northerners also supported the war. Although ardent opponents of slavery protested, most Americans considered westward expansion a boon (see Map 10.3).
Once the war began, battles erupted in a variety of locations. In May 1846, U.S. troops defeated Mexican forces in Palo Alto and Resaca de la Palma. A month later, the U.S. army captured Sonoma, California, with the aid of local settlers. John Frémont then led U.S. forces to Monterey, California, where the navy launched a successful attack and declared the territory part of the United States. That fall, U.S. troops gained important victories at Monterrey, Mexico, just west of the Rio Grande, and Tampico, along the Gulf coast.
Although the Mexican army outnumbered U.S. forces, it failed to capitalize on this advantage. In the northern provinces, Mexican soldiers were ill equipped for major battles, and in the heart of Mexico divisions among political and military leaders limited battlefield success. Still, Mexican soldiers and residents fought fiercely against the American invaders.
Despite major U.S. victories, Santa Anna, who reclaimed the presidency of Mexico during the war, refused to give up. In February 1847, his troops attacked General Taylor’s forces at Buena Vista and nearly secured a victory. Polk then agreed to send General Winfield Scott to Veracruz with 14,000 soldiers. Capturing the port in March, Scott’s army marched on to Mexico City. After a crushing defeat of Santa Anna at Cerro Gordo, the president-general was removed from power, and the new Mexican government sought peace.
The Mexican-American War, 1846-1848 Although a dispute over territory between the Nueces River and the Rio Grande initiated the Mexican-American War, most of the fighting occurred between the Rio Grande and Mexico City. In addition, U.S. forces in California launched battles to claim independence for that region even before gold was discovered there.
With victory ensured, U.S. officials faced a difficult decision: How much Mexican territory should they claim? The U.S. army in central Mexico faced continued guerrilla attacks. Meanwhile Whigs and some northern Democrats denounced the war as a southern conspiracy to expand slavery. In this context, Polk agreed to limit U.S. claims to the northern regions of Mexico. Eager to unite the Democratic Party before the fall election, the president signed the Treaty of Guadalupe Hidalgo in February 1848, and the U.S. Senate ratified it in March. The treaty committed the United States to pay Mexico $15 million in return for control over Texas north and east of the Rio Grande plus California and the New Mexico territory.
Debates over Slavery intensify
News of the U.S. victory traveled quickly across the United States. In the South, planters imagined slavery spreading into the lands acquired from Mexico. Northerners, too, applauded the expansion of U.S. territory but focused on California as a center for agriculture and commerce. Yet the acquisition of new territory only heightened sectional conflicts. Debates over slavery had erupted during the war, with a few northern Democrats joining Whigs in denouncing “the power of slavery” to “govern the country, its Constitutions and laws.” In August 1846, Democratic congressman David Wilmot of Pennsylvania proposed outlawing slavery in all territory acquired from Mexico so that the South could not profit from the war. The Wilmot Proviso passed in the House, but in the Senate, Southerners and proslavery northern Democrats killed it.
The presidential election of 1848 opened with the unresolved question of whether to allow slavery in the territories acquired from Mexico. Polk, exhausted by the war effort and divisions among Democrats, refused to run for a second term. In his place, Democrats nominated Lewis Cass, a senator from Michigan and an ardent expansionist. He had suggested that the United States purchase Cuba from Spain in 1848 and advocated seizing all of Oregon and more of Mexico. Hoping to keep northern antislavery Democrats in the party, Cass campaigned for what he called “squatter sovereignty,” by which residents in each territory would decide whether to make the region free or slave. This strategy put the slavery question on hold but satisfied almost no one.
The Whigs, too, hoped to avoid the slavery issue for fear of losing southern votes. They nominated Mexican-American War hero General Zachary Taylor, a Louisiana slaveholder with no political experience. The Whigs were pleased that he had not taken a stand on slavery in the western territories. But they sought to reassure their northern wing by nominating Millard Fillmore of Buffalo, New York, for vice president. As a member of Congress in the 1830s, he had opposed the annexation of Texas, and he had a reputation for fiscal responsibility and charitable endeavors.
The Liberty Party, disappointed in the Whig ticket, decided to run its own candidate for president. But leaders who hoped to expand their support reconstituted themselves as the Free-Soil Party. Its leaders focused on excluding slaves from the western territories rather than on the moral injustice of slavery. Still, Free-Soilers argued that slavery empowered “aristocratic men” and threatened the rights of “the great mass of the people.” The party nominated former president Martin Van Buren and appealed to small farmers and urban workers who hoped to benefit from western expansion.
Once again, the presence of a third party affected the outcome of the election. While Whigs and Democrats tried to avoid the slavery issue, Free-Soilers demanded attention to it. By focusing on the exclusion of slavery in western territories rather than its abolition, the Free-Soil Party won more adherents in northern states. Indeed, Van Buren won enough northern Democrats so that Cass lost New York State and the 1848 election. Zachary Taylor and the Whigs won, but only by placing a southern slaveholder in the White House.
REVIEW & RELATE
• How did western expansion both benefit Americans and exacerbate conflicts among them?
• How did the Mexican-American War reshape national politics and intensify debates over slavery?