Ejército del Perú
After several defeats that the Peruvian Army suffered in Tacna and Arica, Piérola ordered what was left of the Army to protect the capital. In this way, the Peruvian army and poorly armed citizens that volunteered to the fight were set up to defend Lima. Fooled by the enemy, Piérola expected a Chilean assault from the north of the city, and marched with a large contingent of troops to the city of Ancón.