alec spear timeline mexican american war By MsOlson Period: Jan 1, 1845 to Jan 1, 1849 Mexican American War Mar 1, 1845 Texas Admitted to the Union President John Tyler signed the Congressional Resolution to the Annex. Nov 1, 1845 US Tried to Buy Land (Sidel and Polk) President James Polk sends Sidel to Mexico, to try to buy California and New Mexico. President Herrera refused to meet Sidel to negotiate. Mar 1, 1846 US Troops Stationed at Disputed Border The US army was sent passed the Rio Grande into the disputed territory, May 1, 1846 US Declares War Taylor sent a letter to Polk, who asked Congress to Declare War. Dec 1, 1846 US Victories Kearny arrives in California and fights against the Californios at San Pasqual. Sep 12, 1847 Mexico City Surrendered In the battle of Mexico, the Mexicans had no reinforcements and were forced to surrender to the US. Feb 2, 1848 Treaty of Guadelupe Hidalgo The treaty to end the war was signed and sent quickly to Washington.