After their victory at the Battle of Pangal, the Loyalist forces, composed of approximately 2,400 guerrilla and Mapuche Allies under the command of Vicente Benavides, decided to attack and destroy the city of Los Angeles.

At this juncture, Marshal del Alcázar received forged orders from General Ramón Freire to evacuate the city and move his forces to reinforce Chillán and meet with the main Army that was operating out of Concepción.

Marshal del Alcázar, ignorant of the defeat suffered by the Patriot army at Pangal decided to evacuate the city, taking with him all the inhabitants, who otherwise would have been massacred by the guerrillas.

He left the city on the 25th at the head of the Cazadores de Coquimbo battalion, 50 artillery troops, approximately 150 friendly Mapuche allies and about a thousand civilians, with their properties and animals.

The Patriots surrendered in exchange for their lives and free passage for all the civilians, while Marshal del Alcázar and his officers were to remain as hostages and the surviving soldiers were to incorporate themselves to the guerrilla.