At the end of the Ten Years' War, Periquito was already showing admiration and respect for the mambises, for which he was convinced by Colonel Silverio del Prado, to join the independence cause. At the outbreak of the Little War, Periquito joined the mambises. However, the participation of Pedro Agustín Pérez in the mambí army during said war is not registered. In December 1879, during said war, he was taken prisoner after an enemy attack on the camp where he was staying and was sent to Santiago de Cuba, where he escaped spectacularly by swimming across the bay.