The Battle of Angaco (16 August 1841), was a clash in the Argentine Civil Wars between Unitarian and Federalist forces at Angaco, about 23 kilometres (14 mi) NNE of San Juan, Argentina, that gave an ephemeral advantage to the Unitarians. The federal leader was General José Félix Aldao and the Unitarians were led by Mariano Acha.This was the bloodiest of all battles of the Argentine civil wars.