Mexican War (1846–48)

Origins and Objectives

The Mexican War can be seen as part of a larger pattern of expansionism, including attempts to seize Canada in 1775 and between 1812 and 1814; the acquisition of Florida in 1819 after a series of border clashes led by Gen. Andrew Jackson; and the forced removal of Native Americans to west of the Mississippi River. Undergirding the need for expan-sion was the “understanding” that a sound republic, as the Democratic Party conceived it in the 1830s and 1840s, must be based on a nation of independent farmers and an econ-omy that provided the greatest individual opportunity as well as geographical and social mobility. This mobility, in turn, would prevent the development of a rigid class structure that would undermine democracy. These beliefs were closely entwined within the concept of Manifest Destiny.

Because the desired regions were already occupied by Mexicans and indigenous peoples, the U.S. policy was racist: “Removal, eclipse, or extermination—not accultura-tion and assimilation—awaited the Indians, blacks, and mixed-blood Mexicans on the continent,” notes a promi-nent historian of Jacksonian expansionism (Hietala, 261). The lands were instead to be settled by whites already liv-ing in the United States and by European immigrants whom the Jacksonians welcomed.

The immediate origins of the conflict lay in the Texas Revolution of 1835 to 1836. Anglo American settlers gained independence from Mexico after the battle of San Jacinto. They had captured Pres. Antonio López de Santa Anna, who agreed to independence as the price of his own freedom. But the Mexican government refused to honor the agreement, which had been made under obvious duress. For the next nine years Mexico and the extralegal Republic of Texas fought a protracted though inconclusive border war, and the Mexicans warned the United States that if it annexed Texas, as many Texans desired, it would entail the gravest consequences.

As a result, the U.S. government remained cool to the idea for nearly 10 years. Then Pres. John Tyler, in a bid to shore up his unpopular presidency, made annexation the issue on which he pinned his hopes for reelection in 1844. The attempt did not benefit Tyler's political fortunes, but Democratic candidate James Knox Polk made annexation of Texas a central issue in his successful bid for the presidency. In the final days of his administration, Tyler asked Congress to annex Texas by joint resolution, which was done in February 1845. Thereupon Mexico broke off diplomatic relations with the United States.

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