After the assassination of Francisco Pizarro, in retaliation for his father's execution in 1538, Diego de Almagro II, El Mozo, continued to press claims as the rightful ruler of Peru and as leader of his father's supporters. His claims were largely unsuccessful, however, as Pizarro was succeeded as governor by Cristóbal Vaca de Castro, despite claims from his brother Gonzalo Pizarro, whose claims to join arms against the Almagristas and "El Mozo" largely remained unanswered.

Desperate not to face the same fate as his father after the battle of Las Salinas, Diego de Almagro II gathered an army of supporters but was defeated outside Cuzco at Chupas, on 16 September 1542, the year following Pizarro's murder, and was executed the same day on the city plaza after a brief trial.