Elene T's Mexican American War Timeline By MsOlson Period: Jan 1, 1845 to Jan 1, 1849 Mexican American War Mar 1, 1845 Texas Admitted to the Union Tyler signs Congressional resolution to annex Texas and requests Texas to be admitted to the union. Nov 1, 1845 US Tried to Buy Land (Sidel and Polk) Polk sends John Sidel to Mexico to purchase New Mexico and California. The Mexicans refused the offer and the U.S. resulted in not buying the land. Mar 1, 1846 US Troops Stationed at Disputed Border Taylor's army marched to the disputed border of America and Mexico. There was some controversy on the borders, but both countrys wanted to keep the land to themselves. May 1, 1846 US Declares War Taylor sent a letter to Polk , who then asks the U.S. Congress to declare war with Mexico. Feb 23, 1847 The Battle of Buena Vista The Mexican Army defeated the inexperienced American army of 5,000 troops in the Mexican-American War with the army of 20,000 people who hurried from the north by Santa Anna. Sep 1, 1847 Mexico City Surrendered Mexico City surrendered to the Americans and was occupied by the U.S. army. Feb 1, 1848 Treaty of Guadelupe Hidalgo A peace treaty occured between Mexico and the U.S. and was ratified by the Mexican Congress.