Chris Ns 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 President John Tyler signs congressional relosution to annex Texas. Nov 1, 1845 The US tried to buy land President Polk sends John Slidell to Mexico to try to buy California and New Mexico from Mexico. Apr 1, 1846 Troops stationed at the desputed Boarder Texas joined the Union in 1845, with Mexico breaking relations with the Union and later fighting many battles. May 1, 1846 War is Declared on mexico US declares war on Mexico after they go onto our soil and shed blood. May 8, 1846 Taylor wins the 2 first battles for the US Sep 14, 1847 US Army surrounds mexico city US army surrounds Mexico city and mexico surrenders. Feb 2, 1848 Mexico signs treaty of Guadelupe hidalgo Mexico and the US sign the Treaty of Gualdalupe Hidalgo, establishing a new better border for the US.