General Juan Lavalle had spent more than a year fighting Rosas in Entre Ríos and Corrientes, when he had invaded Buenos Aires Province.

From there, Lamadrid marched towards the Cuyo provinces to open a new war front, thinking José Félix Aldao only had 800-1000 troops from Mendoza at the time, as Lavalle believed.

[9] Yet, at that time reinforcements under Manuel Oribe began arriving adding up to 9,000 troops,[10] but only 6,000 ended up part of the final push as the rest remained defending the Cuyo region.

[13][a] Acha faced the Federalist armies of José Félix Aldao and Nazario Benavídez, governors of the provinces of Mendoza and San Juan, in the Battle of Angaco, one of the bloodiest of the Argentine civil wars.

After Acha had won, he occupied the city of San Juan, but two days later was defeated by Benavídez in the Battle of La Chacarilla, and was shot by order of Aldao.

Aldao ordered 1,000 men to follow up to Catamarca to the north, while the rest remained in La Rioja to prevent an attempt by Lavalle to advance to Cuyo.