The Arauco War was a long-running conflict between colonial Spaniards and the Mapuche people, mostly fought in the Araucanía. The conflict began at first as a reaction to the Spanish conquerors attempting to establish cities and force Mapuches into servitude. It subsequently evolved over time into phases comprising drawn-out sieges, slave-hunting expeditions, pillaging raids, punitive expeditions, and renewed Spanish attempts to secure lost territories. Abduction of women and war rape was common on both sides.After many initial Spanish successes in penetrating Mapuche territory, the Battle of Curalaba in 1598 and the following destruction of the Seven Cities marked 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 17th to the late 18th century a series of parliaments were held between royal governors and Mapuche lonkos and the war devolved to sporadic pillaging carried out by both sides.

In the words of Philip II, this conflict cost the largest number of Spanish lives in the New World, which is why it became known as the Flandes indiano ("Indian Flanders"), in reference to the Eighty Years' War.