Perceiving the intentions of Valdivia to occupy the important post of Penco by a permanent settlement, the adjacent tribes of the Pencones gave notice of this invasion to the great nation of the Araucanians, their neighbours and friends, whose territories began on the southern shore of the Biobio; who, foreseeing that the strangers would soon endeavour to reduce their own country to subjection, determined to succour their distressed allies for their own security. Accordingly, in a _butacoyog_, or general assembly of the Araucanian confederacy, _Aillavalu_ was nominated supreme _toqui_, and was instructed to march immediately with an army to the assistance of the Pencones. In the year 1550, pursuant to the resolutions of the Araucanian confederacy, Aillavalu passed the great river Biobio, at the head of 4000 men, and boldly offered battle to Valdivia, who had advanced to meet him on the banks of the Andalian. The brave Araucanians sustained the first discharges of musquetry from the Spaniards with wonderful resolution, and even made a rapid evolution under its direful effects, by which they assailed at once the front and flank of the Spanish army. By this unexpected courageous assault, and even judicious tactical manoeuvre, the Spaniards were thrown into some disorder, and Valdivia was exposed to imminent danger, having his horse killed under him; but the Spaniards replaced their firm array, forming themselves into a hollow square supported by their cavalry, and successfully resisted every effort of their valiant enemies, of whom they slew great numbers by the superiority of their arms, yet lost at the same time a considerable number of their own men. The battle remained undecided for several hours; when at length, rashly pressing forwards with impetuous bravery, Aillavalu received a mortal wound[65], and many of the most valiant officers and soldiers of the Araucanians being slain, they retired in good order, leaving the field of battle to the Spaniards, who felt no inclination to pursue them after a so dear-bought victory. [Footnote 65: In Ovalle, this general is named Anabillo, and is said to have been made prisoner in the battle.--E.]