Martín García Óñez de Loyola was no minor officer. A grand-nephew of the founder of the Jesuits, he had once captured the last Inca emperor, Túpac Amaru, in the jungles of Peru. Now he governed Chile. In late December 1598 he rode south toward Purén at the head of some fifty soldiers and companions - a small, confident column moving through country the Spanish believed they controlled. On the second night, they made camp at Curalaba. They posted no proper guard. They did not fortify. In the war they were fighting, that was a fatal kind of arrogance, and the men watching them from the dark knew it.

The Mapuche had been tracking the column for days. The vice-toqui Pelantaru, under the supreme toqui Paillamachu, with his lieutenants Anganamón and Guaiquimilla, led three hundred mounted warriors - and here lay the irony of the Arauco War. Within a generation of first contact, the Mapuche had taken the conquerors' own weapon, the horse, and mastered it. Where the Spanish had expected a foe on foot, easily ridden down, they now faced cavalry as good as their own, fighting on home ground in the dark. The warriors struck in the night raid that discipline was meant to prevent. Surprised in their sleep, the governor and nearly every man with him were killed. The Spanish would call it the Disaster of Curalaba, a name heavy with the shock of it: a kingdom's governor dead in the grass, his escort annihilated, by people their own chronicles still dismissed as savages. The word disaster says everything about who was telling the story - and how completely they had misjudged the people they meant to rule.

One ambush, however total, does not end an empire's ambitions. What followed did. News of Curalaba raced through Mapuche country, and the general uprising that the aged toqui Paillamachu had long prepared erupted across the south. Over the next several years the Mapuche swept away every Spanish settlement below the Biobío River - Imperial, Valdivia, Osorno, Villarrica, Santa Cruz de Coya, San Andrés de los Infantes, and Arauco. Historians remember it as the Destruction of the Seven Cities. Thousands of Spaniards died or were captured. An entire colonial frontier, built over half a century, was erased in a few seasons. The Biobío became the border of two worlds.

After Curalaba, Spain stopped trying to conquer the Mapuche and started trying to live beside them. The crown shifted to a defensive line of forts along the Biobío and, in time, to formal treaties - the parlamentos - that gathered Spanish officials and Mapuche leaders to negotiate as something close to equals, recognizing Mapuche territory south of the river. It was an extraordinary thing in the Americas: an Indigenous nation that fought the most powerful empire on earth to a standstill and won, on the ground, an independence that would last until the Chilean state finally pushed south in the late 1800s. For nearly three hundred years, the country below the Biobío answered to no European crown. Today Curalaba is quiet farm country in the Araucanía, easy to pass without a second glance. But in Mapuche memory it is remembered as a victory - one of the great ones, the night the conquest stopped at the river.