The Chilean forces under Commander in chief Manuel Baquedano assaulted and defeated the Allied stronghold guided by Andrés Gamarra garrisoned at Los Angeles hill top.

After a successful scouting mission to discover the allied strength in the area, a massive landing took place at Ilo between 18 and 25 February, disembarking 9,500 men on the Peruvian shore.

The Chilean command decided to launch a second operation against Mollendo, so on 8 March were shipped the 3rd Line Regiment, the Navales and Zapadores battalions, 10 engineers and 30 riders, all under Col. Orozimbo Barboza.

The goal was to fix the Peruvian 1st Division keeping it from aiding the second one which were to be attacked by Baquedano's main force and destroy the docking facilities of Mollendo to obviate future blockading of the port.

This event caused considerable embarrassment to the administration in Santiago and to the army;[3] according to private letters of Lieutenant Rafael Torreblanca, some soldiers were condemned to capital punishment.

At 03:00 hrs, Baquedano marched with 800 riders and a company of the 1st Line Regiment, only to rest the next day at the Ilo river valley, abundant in food and water.

Colonel Muñoz with twelve companies of the 2nd Line and Santiago regiments, an artillery battery and 300 riders was commissioned to attack the Peruvian left flank sited at El Pulpito.

On the Pampa del Arrastrado, on the upper Los Angeles plateau, must be attacked by climbing huge and very even rocks forming a vertical stone wall.

In the meantime, Muñoz' column marched in a narrow path formed by the Tumilaca river's creek, with a company of the 2nd Line Regiment and a Santiago battalion[6] on the vanguard.

For this action, the Atacama Battalion won a commendation and Baquedano was promoted to Commander in Chief of the Chilean Operations Army, replacing Erasmo Escala after the latter resigned.