The Red Battalions were the workers who were hired in the Mexican Revolution to fight against the Zapatistas and Pancho Villa's army. The Mexican Revolution was a civil war that saw various alliances between different class forces pitted against one another for various political reasons; the Red Battalions belonged largely to the Casa del Obrero Mundial, a worker's organization, and were deployed by Carranza in exchange for various rights for workers, to defeat the "peasant counterrevolutionaries" of Zapata and Villa. They were called the Red Battalions because of their communist membership.
The Battalions were ultimately disbanded after Carranza no longer required their forces to subdue the insurgents of the north and the peasant guerillas of the south. On 13 January 1916, amidst strikes incited by the Casa Obrera Mundial, Carranza ordered the last of the Red Battalions to dissolve. Thereafter all labor unrest was suppressed, often violently, and the Casa went into decline.
Cockcroft, James (1992). Mexico: Class Formation, Capital Accumulation, & the State. Monthly Review Press.