This narrative begins with the introduction of the empresario system in Mexico in 1823, a system of land distribution to American farmers and ranchers in an attempt to strengthen the postwar economy following Mexico's independence from Spain. Once welcomed as fellow countrymen, the new settlers, homesteading on land destined to be called Texas, were viewed as enemies when in 1835 they revolted against the government's harsh Centralist rulings. Forced to fight for the principles they believed in, the Texans retaliated for the reprisals against them with armed conflicts against the Mexican military.

Winning independence from Mexico and recognition from the United States as the independent Republic of Texas only intensified the Mexican refusal to accept their loss of Texas as legitimate. The final straw for both sides came when Texas was granted U.S. statehood and 11 American soldiers were ambushed and murdered. As a result, Congress declared war on Mexico, a bloody conflict that resulted in the U.S. gain of 525,000 square miles, land now consisting of California, Nevada, and Utah, most of New Mexico and Arizona, and parts of Colorado and Wyoming.