Chronology of Events Leading to the Mexican-American War

1821

      Mexico wins Independence War with Spain.

1836

• April 21: Texas gains independence from Mexico at the Battle of San Jacinto (Democrat President Martin von Buren stay put, in view also of the forthcoming elections, which he will lose anyway)
• Short history of the Texas Revolution: https://www.youtube.com/watch?v=sfm7CTpyBgU

1844

On April 12, Whig President John Tyler wishes to ratify a Treaty of Annexation but does not have enough votes in the Senate.

A Debate will ensue, concerning also the vocation of US's "manifest destiny"

in Lane Crothers, "The Cultural Routes of Internationalism and Isolationsim in American Foreign Policy. Journal of Transatlantic Studies. Vol. 9, No. 1, March 2011, 21 34

see also, John O'Sullivan, "Annexation"

1845

• March 1: President John Tyler signs official proposal of statehood for Texas. Mexican leaders warn that annexing Texas could lead to war.
• March 4. Democrat James K. Polk elected President

• 1846

  • March 28: General Taylor reaches the Rio Grande near Matamoros.
  • April 23: Mexico declares defensive war vs. United States. It would defend territories under attack but not take the offensive.
  • May 13: US Congress declares war on Mexico.
  • July 4: American settlers in California declare the Bear Flag Republic in Sonoma. The independent republic of California only lasted a few weeks before American forces occupied the area.
  • July 27: Mexican President Paredes leaves Mexico City to deal with a revolt in Guadalajara. He leaves Nicolás Bravo in charge.
  • August 4: Mexican President Nicolás Bravo is deposed by General Mariano Salas as chief executive of Mexico.
  • December 24: Mexican General/President Mariano Salas turns over power to Santa Anna's Vice-president, Valentín Gómez Farías.

  1847

  • February 22-23: The Battle of Buena Vista is the last major battle in the northern theater. The Americans will hold the ground they gained until the end of the war, but not advance any farther.
  1848
  • February 2: Trist and Mexican diplomats agree on the Treaty of Guadalupe Hidalgo.
  • April: Santa Anna escapes from Mexico and goes into exile in Jamaica.
  • March 10: The Treaty of Guadalupe Hidalgo is ratified by the USA. The treaty called for the U.S. to pay US$15 million to Mexico.  It gave the United States the Rio Grande as a boundary for Texas, and gave the U.S. ownership of California and a large area comprising roughly half of New Mexico, most of Arizona, Nevada, and Utah, and parts of Wyoming and Colorado.