Mexican-American War

The Mexican-American War, also usually known in the United States as The Mexican War and in Mexico as la intervención norteamericana (the North American Intervention) or la guerra del 47 (the War of '47), was a military conflict fought between the and Mexico from 1846 to 1848, in the wake of the 1845 U.S. annexation of Texas. Mexico had not recognized the secession of Texas in 1836 and announced its intention to take back what it considered a rebel province.

In the United States, the war was a partisan issue, supported by most Democrats and opposed by most Whigs, with popular belief in the Manifest Destiny of the United States ultimately translating into public support for the war. In Mexico, the war was considered a matter of national pride.

The most important consequence of the war was the Mexican Cession, in which the Mexican territories of California and New Mexico were ceded to the United States. In Mexico, the enormous loss of territory which resulted from the war encouraged the central government to enact policies to colonize its northern territories as a hedge against further losses.

Note: This conflict took place before the point of departure] of many of [[Harry Turtledove's timelines. It is only relevant in Southern Victory, however.  See below.

First Mexican War in Southern Victory
The First Mexican War was a sort of "proving ground" for many of the men who became political and military leaders of the War of Secession, including Ambrose Burnside,Jefferson Davis, Ulysses S. Grant, Thomas Jackson, Albert Sydney Johnston, Robert E. Lee, Abraham Lincoln, James Longstreet, and George McClellan, among others.

For reasons that are not entirely clear, the war fought in 1881 between the United States and the Confederate States and its allies came to be called the Second Mexican War. Presumably, the war was so named because the C.S. sought to annex Mexican territory to expand its own borders, although Mexico played at best a minor role in the second war.