The immediate reason—or excuse, depending on the point of view—for the Mexican-American War (1846–1848) was Texas. In 1836 Texas won its independence from Mexico. The Mexican government later repudiated the treaty and considered Texas still a Mexican province. Mexico threatened war when the United States annexed Texas on 29 December 1845. Relations were already strained because President James K. Polk, through his agent in Mexico, John Slidell, tried to negotiate the purchase of California and lands between it and the United States. The war started when the U.S. Army crossed the...
The immediate reason—or excuse, depending on the point of view—for the Mexican-American War (1846–1848) was Texas. In 1836 Texas won its independence from Mexico. The Mexican government later repudiated the treaty and considered Texas still a Mexican province. Mexico threatened war when the United States annexed Texas on 29 December 1845. Relations were already strained because President James K. Polk, through his agent in Mexico, John Slidell, tried to negotiate the purchase of California and lands between it and the United States. The war started when the U.S. Army crossed the Nueces River, the boundary recognized by Mexico, to establish a fort on the Rio Grande, the boundary recognized by the United States. General Zachary Taylor established Fort Texas near the later site of Brownsville, Texas, and faced a Mexican army six thousand strong, under General Pedro de Ampudia, across the river. Mexico declared war on 23 April 1846; Congress declared war on 13 May 1846. Militarily, the Mexican-American War was a small war, though it served as a proving ground for future Union and Confederate officers in the Civil War. In addition to Taylor's excursion to the Texas border, the United States attacked on three fronts. Colonel Alexander Doniphan led forces that captured Santa Fe and then entered Mexico. General Stephen Watts Kearny conquered cities in Northern Mexico before heading west and joining a popular uprising led by John C. Frémont (the Bear Flag Revolt) to take California. General Winfield Scott led an amphibious invasion near Vera Cruz, Mexico, in March 1847. Within six months Scott had marched his troops to Mexico City, which fell on 14 September 1847. The war exacerbated the growing sectional strife in the United States, especially regarding slavery. Generally, the war was supported in the West and South, but people in the northeastern states saw it as merely a land grab to extend slavery. Many spoke out against the war, including Abraham Lincoln, then a congressman from Illinois. The Democratic congressman from Pennsylvania, David Wilmot, introduced an amendment to the war appropriations bill in August 1846. Called the Wilmot Proviso, the amendment excluded slavery from any new land acquired as a result of the war and was later expanded to include all new territory. Although the proviso managed to pass the House twice, it failed in the Senate, where slaveholding states wielded enough power to defeat it. The Wilmot Proviso became a focal point in the 1848 elections. Frederick Douglass, the famed black abolitionist, adamantly opposed the Mexican-American War, believing it was fought only to extend slavery. Douglass had contended that even the quick recognition of Texas's independence by the United States in 1836 had been motivated by the hope of adding slave territory. When the war began he was traveling in Europe, and he took every opportunity to speak against the war and slavery. Appearing before abolitionist groups in places such as Birmingham, England, Douglass spoke to the irony of a “civilized” nation fighting for slavery against a “semi-barbarous” country that had already abolished it. He also wondered how the war could be a fight for liberty, as the Polk administration called it, when the goal was to gain slave states. The war ended when General Scott took Mexico City, and the two countries signed the Treaty of Guadalupe Hidalgo on 2 February 1848, only nine days before gold was discovered in California. As a result of the treaty and outstanding Texas claims, the United States acquired more than 1 million square miles—over half of what had been, until then, Mexico. Mexico received $15 million, and Mexicans living in the annexed lands became eligible for U.S. citizenship. The war further divided northern and southern interests and, particularly in regard to the status of the new territories, kept slavery a major issue in Congress. To Douglass, the defeat of the Wilmot Proviso by southern interests in the Senate, despite the widespread support of the Whig and Democratic parties, was evidence that slavery as an institution must be beaten not through compromise but by abolition. All the compromises merely gave credence to the institution. Douglass accurately predicted that the only solution to the problem was to dissolve the Union—an easier effort than passing the Wilmot Proviso or any similar provision—and build a new republic. Southern states had nothing to lose, and they acted like it. Control of the Senate by southerners, with the help of a few northern allies, ensured that slavery was not going away, no matter how many lines were drawn, unless something drastic occurred. See also Democratic Party; Douglass, Frederick; Laws and Legislation; Lincoln, Abraham; Polk, James K.; Slavery; Whig Party; and Wilmot Proviso. BibliographyDouglass, Frederick. A Negro View of the Mexican War. In Essential Documents in American History, compiled by Norman P. Desmarais and James H. McGovern. CD-ROM. Ipswich, MA: EBSCO Electronic Publishing, 1998.Frazier, Donald S. The U.S. and Mexico at War: Nineteenth-Century Expansionism and Conflict. New York: Macmillan, 1998.Singletary, Otis A. The Mexican War. Chicago: University of Chicago Press, 1960.
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