Marching on Mexico City

The U.S. Decision to Invade Central Mexico, 1847–1848

Sept. 23, 1846: The third day of the siege of Monterrey during the Mexican-American War. Nathaniel Currier/MPI/Getty Images

Commentary

By the spring of 1847, with the Mexican-American War seeming to stagnate after a year of bitter fighting, the U.S. military had invaded and occupied all of northern Mexico while blockading every major enemy port. Unable to take back its northern provinces or overcome internal political turmoil, the Mexican government refused to seek terms even as it suffered defeat after defeat. The Polk administration, growing impatient in Washington, D.C., consequently made the seminal decision to compel capitulation with a dramatic amphibious invasion of Central Mexico. Driven by a complicated mixture of shifting politics, expansionist policies, and military strategy that cumulatively encouraged aggressive coercion, the presidential directive set conditions for a decisive march on the Mexican capital and the attainment of all American strategic objectives.[1]