Military conflict between the United States of America and Mexico from 1846 to 1848
The Mexican–American War resulted in the U.S. acquiring over half of Mexico's territory, reshaping North American borders and intensifying sectional conflict over slavery.
Key Facts
- Duration
- April 25, 1846 – February 2, 1848
- Peace treaty
- Treaty of Guadalupe Hidalgo (1848)
- U.S. payment to Mexico
- 15 million USD for war damages USD
- Assumed Mexican debt
- 3.25 million USD owed to U.S. citizens USD
- Territories ceded
- Texas, California, Nevada, Utah, parts of AZ, CO, NM, WY
- Diplomatic offer refused
- U.S. offered $25 million for disputed territory and California USD
By the Numbers
Location
Cause → Event → Consequence
The 1845 U.S. annexation of Texas, which Mexico refused to recognize, combined with a disputed border between the Nueces River and the Rio Grande, created tensions. President Polk sent troops into the contested zone; Mexican forces repelled them on April 25, 1846, providing Polk the justification to seek a declaration of war from Congress.
U.S. forces rapidly occupied Santa Fe de Nuevo México and Alta California while the U.S. Navy blockaded the Pacific coast. General Winfield Scott launched an amphibious assault at Veracruz in March 1847, advancing inland to capture Mexico City in September 1847, effectively defeating Mexican military resistance and compelling peace negotiations.
The 1848 Treaty of Guadalupe Hidalgo ended the war, with Mexico ceding vast territories including present-day California, Nevada, Utah, and parts of several other states. The acquisition reignited fierce debate over the expansion of slavery into new territories, deepening sectional divisions that many historians link as a contributing factor to the American Civil War.
Belligerents & Mobilization Analysis
Side A
1 belligerent
James K. Polk, Winfield Scott, Nicholas Trist (peace envoy).
Side B
1 belligerent
Antonio López de Santa Anna.