|Battle of Peteroa|
|Part of Arauco War|
|Commanders and leaders|
|40 Spanish soldiers, 400 yanakuna ||300 soldiers|
|Casualties and losses|
|Two Spaniards were killed||200 killed|
Battle of Peteroa was a battle in the Arauco War in 1556, in a plain beside a river in the Mataquito River valley, called Peteroa. The battle was between the Spanish forces of Pedro de Villagra, and Mapuche headed by their toqui Lautaro.
Following the destruction of Concepcion and Angol in 1554, the Mapuche suffered from the effects of a famine and an epidemic for two years. Meanwhile, in the north the victories of Lautauro led to uprisings by the previously subdued Promaucaes of Gualemo and the Picunche in the Aconcagua Valley, but these were put down. In 1556, the Promauces sent a message to the Mapuche of Arauco promising food to support their army and warriors to join it in a war against the Spanish in Santiago.
In May 1556 Lautaro was able to lead a force north of the Bio Bio River expecting to instigate a rebellion there among subjugated Mapuche north of that river and the Promaucaes north of the Itata River. Lautaro began recruiting warriors among these people, conquered by Pedro Valdivia years before, who were now inspired to revolt by the previous successes of Lautaro.
Lautaro led his force of Mapuche to the north towards Santiago. After crossing the Maule River he encamped near modern Teno, at a place called Peteroa. But when he entered the places subject to Santiago, he began taking reprisals against the Promaucaes who refused to join him, doing great damage and depopulating the land. Spanish and Indian refugees fled to the city for aid and protection. After he was victorious over the first probe from Santiago of twenty Spanish horsemen under Diego Cano, Lautaro built an earthen fort around his camp flooding the land around it to hamper the Spaniards from attacking it.
Later a larger force under Pedro de Villagra sent from Santiago clashed with Lautaro's army in and around their fortress in Peteroa over a few days, killing 500 of their number for the loss of two Spaniards but were not able to take the position. However the losses in the battle and the approach of Spanish reinforcements persuaded Lautaro to retire towards the Maule River with the intention of establishing himself there. However a Spanish cavalry detachment under Juan Godíñez, caught and nearly destroyed a detachment of his army there, persuading Lautaro to move further south beyond the Itata River to recover his strength.