The naval Incident Hostile_encounter of Pacocha took place Process_start on 29 May 1877 when Nicolás de Piérola was leading Causation a revolution Change_of_leadership to overthrow Change_of_leadership then Peruvian President Mariano Ignacio Prado .

Piérola 's supporters Supporting used Using the Peruvian monitor Scrutiny `` Huáscar '' as a raiding ship .

The Chilean army led Conquering by Gen. Manuel Baquedano inflicted a harsh defeat Conquering on the Peruvian army commanded Control by the Supreme Chief Nicolás de Piérola .