This site declared "Outstanding" by
Britannica Internet Guide

The U.S.-Mexican War, 1846-1848
Home History Images Documents Maps Historical Sites Chronology Resources Statistics

Return to U.S.-Mexican War Home Page

A Chronology of the U.S.-Mexican War
Battles, Skirmishes & Other Important Events

1845-6    1846    1847    1848

A Brief Prelude to the Mexican War
By William J. Bozic, Jr./ May 12, 2004

  • Early 1845: President Antonio Lopez de Santa Ana is overthrown, followed by a power-struggle in which Jose Joaquin Herrera emerges as the new leader of Mexico.
  • March 1, 1845: U.S. President John Tyler signs Joint Resolution of Congress, offering Texas terms of annexation.
  • March 4, 1845: James Knox Polk inaugurated President of the United States.
  • March 31, 1845: Mexican Minister to the U.S., Juan Almonte, requests his passport and issues a proclamation that defames the U.S.A. and indicates a state of war exists.
  • April 5, 1845: Mexican President Herrera sends Antonio Lopez de Santa Ana into exile in Cuba.
  • June 4, 1845: Mexican President Herrera issues war proclamation.
  • July 4, 1845: Texas votes in favor of annexation. (Mexico does not recognize Texas independence or the annexation)
  • July 1845: President James K. Polk orders General Zachary Taylor to organize an army for occupation of Corpus Christi, Texas and Commodore David Conner to prepare a squadron for the Gulf of Mexico.
  • October, 1845: President Herrera agrees to meet US Commissioner John Slidell to discuss peace (Texas). Slidell is actually sent to discuss a bigger purchase.
  • October-November 1845: Rumors in Mexican press undermine Herrera by accusations he is a traitor intent on giving away Mexican land, so Herrera refuses to meet Slidell. Political opponents of Herrera call for military action.
  • December 1845: With troops intended for the border (Matamoros), General Mariano Paredes forces Mexican President Jose Joaquin Herrera from office.
  • January 1846: Mariano Paredes is new President of Mexico.
  • January 1846: President Polk orders Zachary Taylor and troops from Corpus Christi to Rio Grande and David Conner's squadron to Vera Cruz.
  • March 1846: John Slidell leaves Mexico.
  • March 1846: Taylor marches to Rio Grande
  • March 18: In Matamoros, Mexican General Francisco Mejia issues a proclamation of war then sends it to Zachary Taylor.
  • April: General Mariano Arista replaces General Mejia at Matamoros.
  • April 25: Thornton Affair- US Dragoons attacked by Mexican Cavalry on US side of Rio Grande. Americans are killed, wounded, & captured. (Brownsville, Texas)
  • May 3-8: Fort Texas Siege (Brownsville, Texas)
  • May 8: Battle of Palo Alto (Brownsville, Texas)
  • May 9: Battle of Resaca de la Palma (Brownsville, Texas)
  • May 9: News arrives in Washington of the Thornton Affair.
  • May 13: US Declares war on Mexico. President Polk says "American blood has been shed on American soil" in reference to the Thornton Affair.

Butler, Steven R. A Documentary History of the Mexican War (Richardson, Texas: DMWV, 1994).
Winders, Richard Bruce. Mr. Polk's Army: The American Military Experience in the Mexican War. (College Station, Texas: Texas A & M University Press, 1997).

Return to The U.S.-Mexican War, 1846-1848

The information contained in this site is provided free-of-charge for educational purposes only.

Designed and Maintained for the Descendants of Mexican War Veterans by:

Copyright © 1996 - 2022, Descendants of Mexican War Veterans
All Rights Reserved. Limited use rights may be granted by written or electronic permission.