THE MEXICAN WAR was fought from April 1846 to February of 1848 lasting one year and nine months. It is one of the more controversial wars in American history. Obstensibly begun due to conflicts with Mexico over disputed border claims between the two nations, it finally ended with the Treaty of Guadalupe Hidalgo. The treaty established the Rio Grande as the border and settled Mexican citizens claims against the U. S. by paying them 3.5 million dollars, plus another 15 million to the Mexican government in exchange for the Mexican Cession. The Cession gave California and the American southwest to the U.S. including all or part of ten states. The wars political nature and the fact that it cost Mexico about 55% of its territory has been one of the major complicating factors in the U. S. relationship with Mexico ever since. The war included the involvement of President Polk and five future U. S. Presidents four of which fought in the war, (Taylor, Pierce, Grant, Fillmore) and one future President named Lincoln. As a member of the Congress, Lincoln strongly opposed the war believing it would lead to an expansion of slavery. Other prominent soldiers included Robert E. Lee and Kit Carson.
Ironically, the U. S. had offered Mexico 45 million dollars for California and what later became New Mexico more than a year before the war.