The "Army of the Centre," under General Wool, moving from San Antonio de Bexar on Chihuahua; 3d.

The "Army of Occupation," on the Rio Grande, under General Taylor, moving from Corpus Christi on Matamoras, Monterey, and Saltillo; and 4th.

The "Main Army," under General Scott, moving from Vera Cruz on the capital of Mexico.
The Army of the West, under General Kearny, moved upon a separate and distinct line of operations, having no strategic relations to the other three; its objects were the conquest and occupation of New Mexico and Upper California.

The first was readily accomplished; but the general then detached so large a force to operate on Chihuahua after the diversion of Wool's column, that his expedition to California must have utterly failed without the assistance of the naval forces in the Pacific.
The lines of Taylor and Wool were evidently ill chosen, being so distant as to afford the enemy an opportunity to take a central position between them.

Fortunately Wool proceeded no further than Monclova, and then turned off to occupy Parras, thus coming under the immediate command of General Taylor.