Eric P.'s Mexican-American War Timeline By MsOlson Jan 6, 1845 Texas admitted to the Union Period: Jan 8, 1845 to Jan 25, 1849 Eric P. Mex-Amer War Jan 10, 1845 Us tried to Buy Land (Sidel and Polk) Apr 8, 1846 US Troops Stationed at disputed border Oct 8, 1846 US Declares war Apr 8, 1847 Mexico City Surrendered Sep 12, 1847 Battle of Chapultepec Apr 8, 1848 Treaty of Guadelupe Hidago