Guerra de Mexico

 On this day in 1848, the Treaty of Guadalupe Hidalgo was signed, ending the Mexican-American War. After nearly two years of fighting, the U.S. Army had completely overwhelmed the forces of Mexican President and General Antonio Lopez de Santa Anna. As such, the terms of peace were exceedingly in the United States’ favor. These included the establishment of the Rio Grande River as the border between Texas and Mexico, and the ceding of land that today includes most of the states of California, Nevada, Utah, Colorado, New Mexico, and Arizona. (The remainder of the Southwest was acquired by the Gadsden Purchase in 1853).

This massive territorial expansion had been a stated goal of U.S. President James K. Polk, and directly fed into the idea of Manifest Destiny (that the US was destined to range “from sea to shining sea”). But it also directly fueled political tensions over the issue of slavery, and its expansion into these newly acquired territories. Mexico had abolished slavery in 1829, and so many of the new American citizens living in the West were divided. Implementation of slavery in these areas would give power to the institution and its champions, and already the fear of what this could mean spread throughout the country.

In the end, after numerous political debates and minor compromises, fears were momentarily abated. Other than Texas, no other part of the Mexican Cession would choose to adopt the institution. But the issue of the hypothetical expansion of slavery would hang over the head of the nation until the Civil War brought the conflict to its greatest point. As the poet Ralph Waldo Emerson so prophetically put it prior to the start of the War: “The U.S. will conquer Mexico, but it will be as the man swallows the arsenic, which brings him down in turn. Mexico will poison us."