The Arauco War is a long-running conflict between colonial Spaniards and the Mapuche people, mostly fought in the Araucanía.

After many initial Spanish successes in penetrating Mapuche territory, the Battle of Curalaba in 1598 and the following destruction of the Seven Cities marks a turning point in the war leading to the establishment of a clear frontier between the Spanish domains and the land of the independent Mapuche.

From the seventeenth to the late eighteenth century, a series of parliaments are held between royal governors and Mapuche lonkos and the war devolves to sporadic pillaging carried out by Spanish soldiers as well as Mapuches and outlaws.The Chilean War of Independence brings new hostilities to the frontier, with different factions of Spaniards, Chileans and Mapuches fighting for independence, monarchy, or personal gain.

Mapuche independence finally ends with the Chilean occupation of Araucanía between 1861 and 1883.

The modern Mapuche conflict is partially inspired by the Arauco War.