The Mexican-American War killed thousands of American and Mexican soldiers. The Mexican-American War marked the first U.S. armed conflict chiefly fought on foreign soil.(https://www.history.com/topics/mexican-american-war).The war was over the fact that America annexed Texas while it was independent from Mexico. The Rio Grande also had a very big part of the war because it is where some the first battles began. In 1821 Mexico became independent from Spain, Mexico at the time owned Texas and California, but in 1836 Texas became independent and tried to be annexed into America. After a few years in 1844 Jame K Polk became president and a year later annexed Texas into America on their manifest destiny. In 1846 America went into a justified
