The U.S.-Mexican War

1846-1848

Motivation

California• President Polk, motivated by

Manifest Destiny, desired California and desperately wanted to buy it from Mexico

• Unable to buy it because of bitter relations between the two nations

• In 1845, Polk sent John Slidell to Mexico City to offer $25 million for California, the Mexicans wouldn’t even allow him to present his “insulting” proposition

Mexican Debt

• The U.S. had claims against Mexico for $3 million in American damages

• Mexico agreed to pay up but defaulted on its payments

Texas

• Mexico threatened war if the U.S. annexed Texas

• Then the U.S. annexed Texas

• Mexico pulled its ambassador to Washington, cutting off diplomatic relations

Texan Boundary Dispute

• SW boundary had been Nueces River but the expansive Texans claimed more southerly Rio Grande

• Polk felt morally obligated to defend Texas in its claim, once it was annexed

• Mexicans believed that all of Texas was still theirs, just temporarily in revolt, and a fight over the two rivers seemed pointless

War

Polk’s Eagerness• Polk sent General Zachary

Taylor with four thousand troops from the Nueces River to the Rio Grande

• On May 9, 1846, he considered waging war before Mexican attack on the basis of unpaid claims and Mexican rejection of Slidell’s offer

• Cabinet felt as if he should wait until the Mexican troops fired

• That very night, news of bloodshed arrived

“Jimmy Polk’s War”

• After hearing that Mexican troops killed Americans, Polk spoke to Congress

• He claimed that they did everything they could do to avoid a clash but the Mexicans were persistent and killed Americans on “American soil”

• The patriotic Congress voted for war but Polk’s claims were twisting the truth

Santa Anna

• The exiled dictator persuaded Polk into allowing him to return to Mexico, saying he would sell out his country

• Instead, he proceeded to rally his countrymen to defend their soil

California Bear Flag Republic

• American operations in the SW and California were completely successful

• General Stephen W. Kearny led 1700 troops from Leavenworth to Santa Fe which was easily captured

• Before Kearny could get to California, it was already won

• Captain John C. Frémont just “happened” to be there when the war started up

Buena Vista

• Zachary Taylor fought his way into Mexico where after several victories, he reached Buena Vista

• There his weakened force was attacked by march-weary Mexican troops under Santa Anna

• Mexicans were repulsed but with extreme difficulty

General Winfield Scott

• Hampered by small number of troops, expiring enlistments, bigger enemy, mountainous terrain, disease, and political back-biting at home

• Still battled way to Mexico City in one of the most brilliant campaigns in American military history

Resolution

Nicholas P. Trist

• “Blundering” chief clerk of the State Department, sent with Scott’s army to make treaty

• Arranged ceasefire with Santa Anna where S.A. pocketed $10,000 and used time to strengthen defenses

• Polk, disgusted in Trist, recalled him to Washington then Trist wrote a 65-page letter explaining why he wasn’t coming back

Treaty of Guadalupe Hidalgo

• Signed by Trist on February 2, 1848

• Confirmed American title to Texas

• Gave up land stretching westward to Oregon, including California (about one-half of Mexico)

• U.S. to pay $15 million for land and assumed the Mexican debt

Overview

• Cost thirteen thousand American lives (most by disease)

• Fruits of fighting were enormous—an addition greater than the Louisiana Purchase

• Provided battlefield experience for a lot of Civil War soldiers, both Robert E. Lee and Ulysses S. Grant participated