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Mexico gains independence from Spain
In early 1821, Agustín de Iturbide, the leader of the Royalist forces, negotiated the Plan of Iguala with Vicente Guerrero. Under the plan, Mexico would be established as an independent constitutional monarchy, the privileged position of the Catholic Church would be maintained, and Mexicans of Spanish descent would be regarded as equals to pure Spaniards. Mexicans of mixed or pure Indian blood would have lesser rights. -
Americans are defeated at the Alamo
For the Texans, the Battle of the Alamo became a symbol of heroic resistance and a rallying cry in their struggle for independence. On April 21, 1836, Sam Houston and some 800 Texans defeated Santa Anna's Mexican force of 1,500 men at San Jacinto (near the site of present-day Houston), shouting “Remember the Alamo!”. -
John Tyler becomes president
A strong supporter of states' rights, Tyler was a Democratic-Republican; however, in 1840 he ran for the vice presidency on the Whig ticket. As president, Tyler clashed with the Whigs, who later tried, unsuccessfully, to impeach him. Among his administration's accomplishments was the 1845 annexation of Texas. -
Americans and British agree to the Webster- Ashburton Treaty
During Daniel Webster’s first term as Secretary of State (1841–1843), the primary foreign policy issues involved Great Britain. These included the northeast borders of the United States, the involvement of American citizens in the Canadian rebellion of 1837, and the suppression of the international slave trade. The Webster-Ashburton Treaty, signed August 9, 1842, resolved these frictions in Anglo-American relations. -
U.S annexes Texas
President Martin van Buren refrained from annexing Texas after the Mexicans threatened war. Accordingly, while the United States extended diplomatic recognition to Texas, it took no further action concerning annexation until 1844, when President John Tyler restarted negotiations with the Republic of Texas. His efforts culminated on April 12 in a Treaty of Annexation, an event that caused Mexico to sever diplomatic relations with United States. -
Mexican- American War begins
It pitted a politically divided and militarily unprepared Mexico against the expansionist-minded administration of U.S. President James K. Polk, who believed the United States had a “manifest destiny” to spread across the continent to the Pacific Ocean. A border skirmish along the Rio Grande started off the fighting and was followed by a series of U.S. victories. -
Treaty of Guadalupe Hidalgo ends the Mexican American War
The treaty added an additional 525,000 square miles to United States territory, including the including the land that makes up all or parts of present-day Arizona, California, Colorado, Nevada, New Mexico, Utah and Wyoming. Mexico also gave up all claims to Texas and recognized the Rio Grande as America’s southern boundary. -
With the Gadsden Purchase, the United States acquires an additional 30,000 square miles from Mexico
The Gadsden Purchase, or Treaty, was an agreement between the United States and Mexico, finalized in 1854, in which the United States agreed to pay Mexico $10 million for a 29,670 square mile portion of Mexico that later became part of Arizona and New Mexico. Gadsden’s Purchase provided the land necessary for a southern transcontinental railroad and attempted to resolve conflicts that lingered after the Mexican-American War.
