On this day in 1848 Mexico ratified the Treaty of Guadalupe Hidalgo, thus ending the Mexican-American War. The war broke out in 1846 after the United States, as a last act of outgoing President John Tyler, annexed Texas from Mexico in 1845. Texas was Mexican territory but had declared itself independent in 1836 and requested to join the United States. The American debate over Texas revolved mostly around the slavery issue, as the admission of Texas (a slaveholding region) to the Union would once again flare sectional tensions over the divisive issue of slavery in the United States. The annexation heightened tensions between Mexico and the United States, and war eventually broke out in 1846 when a Mexican cavalry unit killed some American soldiers. The war lasted for almost two years, ending with a resounding victory for the United States.
The Treaty of Guadalupe Hidalgo officially ended the war but also provided for the sale of a huge portion of Mexican land to America – the ‘Mexican Cession’ – for $15 million. This new area of land encompassed modern California, Nevada, Utah, much of Arizona and New Mexico and small parts of Colorado and Wyoming. Many Americans, especially the Democratic administration of James K. Polk, celebrated the expansion of America to the Pacific coast. However the acquisition raised further problems over the slavery issue which were eventually settled by the controversial Compromise of 1850, often considered a mere armistice which eventually led the nation into civil war. In fact, one historian (Gary Kornblith) has argued that no Mexican War, no Civil War. He pinpoints the ‘point of no return’ as the expansionist Polk’s election in 1844 over the more moderate Whig Henry Clay. Without this popular endorsement of Manifest Destiny – the idea that America’s destiny is to expand across the continent – Tyler would have been unable to push annexation through Congress. There would thus have been no war, no Mexican Cession to debate slavery over, no Compromise of 1850 which enflared sectional tensions, and thus no secession and no war. It is an interesting argument and while many may disagree, shows just how important the Mexican War, and the treaty that ended it, is to American history.
“The United States will conquer Mexico, but it will be as the man swallows the arsenic, which brings him down in turn. Mexico will poison us.”
– Ralph Waldo Emerson’s prescient warning over war with Mexico as it would incite the slavery debate