Prior to the Mexican-American War, Texas gained independence from Mexico, and was admitted to the Union in 1845 by President Tyler. Tyler admitted Texas to the Union because he saw strong support for the Democratic Manifest Destiny platform. The annexation of Texas began America’s quest for expansion across the North American territory.
We have California!
President Polk ran on a Manifest Destiny platform, and began efforts to gain more territory once in office. Polk wanted California and New Mexico, and first attempted to purchase the territory peacefully. Mexico refused to meet with US ambassadors, so Polk began to send the military and exploratory parties out to Mexico’s territories.
Mexico felt threatened after Polk sent General Taylor and a 4000 men army to the Rio Grande. In April of 1846, they attacked the American troops. Polk claimed that Mexico had killed Americans on US soil to gain national support when he asked Congress to declare war.
We lost everything!
Stephen Kearny was able to take New Mexico peacefully and without any bloodshed. In California, John C. Fremont led a group of settlers to seize the town of Sonoma. Kearny then arrived from New Mexico to bring California under complete US Control.
The war ended in 1848, with the Treaty of Guadalupe Hidalgo. The U.S agreed to pay $15 million, in exchange, and Mexico agreeing to the Rio Grande as the southern border of TX. The Gadsden Purchase of 1853 had the U.S pay $10 million for additional territory.
The Mexican-American War is better characterized as an invasion of Mexico by the United States. Mexico was attempting to defend its land from a country trying to expand its territory, and was forcefully entered into a war. In the end, Mexico lost 25,000 lives and half of its land, while the US doubled in size.