Mexican–American War
The Mexican–American War, known in the United States as the Mexican War and in Mexico as the United States intervention in Mexico, was an invasion of Mexico by the United States that lasted from April 25, 1846, to February 2, 1848. The conflict followed the 1845 American annexation of Texas, a territory Mexico still claimed because it refused to recognize the Treaties of Velasco, which had been signed by President Antonio López de Santa Anna after his capture during the Texas Revolution. Although the Republic of Texas functioned as an independent country, most of its Anglo-American settlers, who had moved there after 1822, desired annexation by the United States. This annexation had previously been blocked by sectional politics over slavery, as Texas would enter as a slave state and upset the balance between Northern free states and Southern slave states. In the 1844 presidential election, Democrat James K. Polk won on a platform of expanding U.S. territory to Oregon, California, and Texas by any means. The boundary between Texas and Mexico was disputed: the U.S. and the Republic of Texas claimed the Rio Grande, while Mexico insisted on the more northerly Nueces River. Polk sent a diplomatic mission to buy the disputed territory, California, and the lands between for $25 million, but Mexico refused. Polk then ordered 80 soldiers into the disputed area to the Rio Grande, ignoring Mexican demands to withdraw. Mexico interpreted this as an attack and repelled the U.S. forces on April 25, 1846, which Polk used to persuade Congress to declare war. U.S. forces quickly occupied Santa Fe de Nuevo México and moved against Alta California before turning south. The U.S. Navy blockaded the Baja California coast. Under Major General Winfield Scott, the U.S. Army landed at Veracruz and captured Mexico City in September 1847. Despite battlefield defeat, negotiating peace was difficult, as some Mexican factions refused to accept territorial loss. Polk relieved his peace envoy, Nicholas Trist, but Trist ignored the order and concluded the Treaty of Guadalupe Hidalgo in 1848. Mexico recognized the cession of present-day Texas, California, Nevada, Utah, and parts of Arizona, Colorado, New Mexico, and Wyoming. The U.S. paid $15 million for war damage and assumed $3.25 million in Mexican debts. Mexico accepted the Rio Grande as its northern border. The war inspired patriotism in
- belligerents
- United States vs. Mexico
- outcome
- U.S. victory; Treaty of Guadalupe Hidalgo
- territorial_changes
- Mexico ceded present-day Texas, California, Nevada, Utah, and parts of Arizona, Colorado, New Mexico, and Wyoming
- key_commander
- Major General Winfield Scott (U.S.)
Lore & Background
The Mexican–American War (1846–1848) was an invasion of Mexico by the United States, triggered by the 1845 U.S. annexation of Texas, which Mexico still claimed as its own territory. The core dispute centered on the boundary: the United States asserted the Rio Grande as the border, while Mexico insisted on the more northerly Nueces River. President James K. Polk, elected on a platform of territorial expansion, sent a diplomatic mission offering $25 million for the disputed land, California, and the territory between, but Mexico refused. Polk then ordered 80 soldiers into the disputed area to the Rio Grande; Mexican forces repelled them on April 25, 1846, which Polk used to secure a U.S. declaration of war. U.S. forces quickly occupied Santa Fe de Nuevo México and Alta California, then moved south. Major General Winfield Scott led an amphibious landing at Veracruz on March 9, 1847, and captured Mexico City that September. Despite battlefield defeat, Mexican factions resisted recognizing territorial loss. Polk’s peace envoy, Nicholas Trist, ignored his dismissal and negotiated the 1848 Treaty of Guadalupe Hidalgo, ending the war. Mexico recognized the cession of present-day Texas, California, Nevada, Utah, and parts of Arizona, Colorado, New Mexico, and Wyoming. The U.S. paid $15 million for war damage and assumed $3.25 million in Mexican debts. Mexico accepted the Rio Grande as its northern border. The war intensified U.S. slavery debates and is seen by some scholars as a precursor to the American Civil War. In Mexico, it worsened political turmoil, caused heavy military and civilian casualties, undermined financial stability, and resulted in the loss of over half its territory.
Reader's Guide
The Mexican–American War was a pivotal conflict that expanded U.S. territory dramatically but intensified the debate over slavery in the United States. The victory and territorial expansion inspired patriotism among some Americans, but the war drew fierce criticism for casualties, monetary cost, and heavy-handedness. In Mexico, the war worsened domestic political turmoil, led to a loss of national prestige, and undermined financial foundations. Many West Point-trained officers gained experience in the war and later played prominent roles in the American Civil War. The Treaty of Guadalupe Hidalgo ended the war, with Mexico recognizing the cession of vast territories and accepting the Rio Grande as its northern border.
Did You Know?
- The war is known in Mexico as the United States intervention in Mexico.
- Polk's peace envoy, Nicholas Trist, ignored his removal from post and successfully concluded the Treaty of Guadalupe Hidalgo.
- The U.S. paid $15 million for physical damage and assumed $3.25 million of Mexican debt to U.S. citizens.
- Some scholars see the Mexican–American War as leading to the American Civil War.
Frequently Asked Questions
Who is Mexican–American War?
The Mexican–American War was a 1846–1848 armed conflict between the United States and Mexico, listed as entry 1 in the Major Wars 1-20 fan encyclopedia.
What are Mexican–American War's powers/role?
The war functioned as the vehicle for American westward expansion, with the two nations' armies clashing across a broad front. Major General Winfield Scott commanded the principal U.S. expedition that ultimately overran Mexican defenses.
How does Mexican–American War's story end?
The story closes with a clear U.S. victory sealed by the 1848 Treaty of Guadalupe Hidalgo. Under its terms, Mexico relinquished enormous tracts of land, including present-day California, Nevada, Utah, and sections of several other states.
Why is Mexican–American War important?
The war is significant because it stripped Mexico of over half its pre-war territory and redrew the map of the continent. Many scholars also draw a direct thread from that expansion to the sectional disputes that erupted into the American Civil War.
What territory changed hands after Mexican–American War?
Mexico ceded what is now Texas, California, Nevada, Utah, and portions of Arizona, Colorado, New Mexico, and Wyoming to the United States. That single transfer effectively more than doubled the area of the young nation.
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