The Spanish on their side, were warned from the beginning of the courage and combative impulse of the Mapuche, but they took dozens of years to realise the power of their military imagination and the tenacity of their warrior energy...” (Encina). In his campaign of the Bio-Bio, and after fierce fights with the Mapuches, Pedro de Valdivia manages to reach the Valley of Andalién. This occurred on February 22nd , 1550. On the second day of camping in the land where today sits the city of Concepción, an army of indigenous inhabitants falls upon the Spanish camp; an army that some historians estimated around fifteen thousand. The battle unfolds in a bloody manner and in the moment that Pedro de Valdivia feels the battle is lost, he decides, as a last resort, to stand his ground and form a group of spikes and spears that, aided by the arquebusiers, re-establishes combat to disperse the indigenous warriors.