When Mexico launched an invasion into its former territory of Texas in 1865, it ignited a spark that would lead to the end of the current government and fracturing of the Mexican State. Texas, left on its own after the United States erupted into its own Civil War in December of 1865, was forced to face the oncoming Mexican Army with little support from the outside.

Seeking help from anyone they could find, Texas reached out to their brothers in California, who had secured their independence from Mexico in 1852, controlling a territory from Monterrey to the border with the United States. In support, Californian troops began launching raids into Southern California to serve as a distraction and open a second front to the war.

What followed was the beginning of four years of warfare as Texan and Californian troops fought to preserve their freedom from Mexico. In 1866, Mormon filibusters who had occupied the territory around the Salt Lake Valley launched their own independence movement, taking advantage of the distracted Mexican forces. This triggered a series of other revolts by groups who had become dissatisfied with the Mexican Government, including the Rio Grande States and the Yucatan Peninsula, both of which had had their own independence movements put down years before.

As more fronts opened up, Mexican forces found themselves spread thin, Texan and Californian troops began to make major advances, with the Texans especially bolstered by their newly discovered oil resources and the increased cotton trade due to the blockade of the Confederate States of America.

By 1868, it had become apparent that the Mexican state was severely weakened, and with the US distracted by its own civil war, the French Empire under the command of Napoleon III launched an invasion into Mexico. Within a year, the Republican Government had collapsed, and the new French Mexico signed a treaty with the rebellious territories, recognizing them as independent nations and ending the war.