The Unitarians won a transitory victory, because soon after Federalists retook the city of San Juan and defeated, captured and killed Acha.

His force spent the night in a place called the paddocks of Daniel Marcó, in the Albardón Department, bordering Angaco.

General Acha, knowing that Benavídez had returned with his column, left the city and went north to meet it with a small group of Unitarian reinforcements from San Juan.

On the morning of 15 August 1841 the Unitarian vanguard, the Brizuela Battalion led by Juan Crisóstomo Álvarez, spotted the federal camp, which was at the ranch with horses unsaddled.

Acha, made confident by the partial success that his vanguard had achieved, had time to choose the most advantageous spot to wait for the enemy.

On 16 August 1841, at 8:00 on a cold day, Benavídez advanced with his cavalry in a fierce attack before main Federalist army had reached the battlefield, and dashed against his enemies.

Aldao then ordered his cavalry to attack the flanks, where the Unitarian guns caused great destruction and forced it to retire for the second time.

During the confusion of the cavalry attack, Aldao wanted to exploit the situation and ordered Francisco Díaz to advance at the trot towards the line of enemy artillery and infantry.

The Unitarian guns fired point blank at Díaz's troops, who closed in hand-to-hand combat with bayonets and sabers.

Aldao, furious at being unable to win despite great numerical superiority, quickly reformed the two infantry battalions and ordered a new attack, without giving time for the cavalry, which was dispersed, to rearm.

Aldao ordered a new maneuver, with commander Rodríguez to attack with cavalry from the rear, but the Unitarians had been warned and shot at close range.

Aldao, overcome by despair, personally led the remnants of his infantry and advanced to the ditch, where his men threw themselves flat on the ground, firing intensely at a range of 5 metres (16 ft).

A few days later at the Battle of La Chacarilla, Nazario Benavidez defeated the Unitarian fighters who had survived Angaco, recovered the city of San Juan and captured General Acha, who would be executed shortly afterwards.

General Lamadrid continued his slow advance towards the cities of San Juan and then Mendoza, which he held in turn.

Persecuted first by Benavidez and then by General Angel Pacheco, he was finally defeated in the Battle of Rodeo del Medio, which ended Unitarian resistance for a decade.