On learning the death of Valdivia, as formerly related, Philip II. gave charge of the government and conquest of Chili to Alderete, the agent who had been sent by Valdivia into Spain, and furnished him for this purpose with six hundred regular troops.  During the voyage to the Tierra Firma, the ship was set on fire by accident, by his sister who was accustomed to read in bed; and of the whole number on board, Alderete and three soldiers alone escaped to Porto Bello.  Overcome with grief and disappointment at this melancholy catastrophe, Alderete died soon after in the small island of Taboga in the gulf of Panama.  When informed of this disaster, and of the threatening aspect of affairs in Chili in consequence of the untoward events in the Araucanian war, the marquis of Canete, then viceroy of Peru, appointed his son Don Garcia Hurtado de Mendoza, to the vacant government.  As this charge had become both important and dangerous, the marquis resolved that his son should be accompanied by such a body of forces as might be able to support his authority, and might enable him successfully to terminate the war against the Araucanians.  As the civil dissensions in Peru were now at an end, and that country abounded in military adventurers eager for employment, he was soon able to levy a respectable force of horse and foot for this expedition.  The infantry, all well equipped and appointed, with a great quantity of military stores; embarked in ten ships under the command of Don Garcia in person; and the cavalry marched by land under the orders of Garcia Ramon, who was appointed quarter-master-general of Chili.

Don Garcia arrived with his fleet in safety in the Bay of Conception, in the month of April 1557, and came to anchor near the island of Quiriquina, which was chosen as the headquarters as a place of great security.  The scanty population of the island attempted to oppose the disembarkation of the troops, but being soon dispersed by the artillery, they retired in their piraguas to the continent.  A small number being made prisoners, the governor sent two or three of them with a message to the Araucanians, to inform them of his arrival, and that he was desirous to settle a lasting peace with them on fair terms.  In an assembly of the Ulmens to deliberate upon this message, the general opinion was that no propositions ought to be listened to from an enemy who had returned in greater force than ever, under the idea that any terms they might propose would necessarily be treacherous and unfair.  Old Colocolo observed, however, that no injury could arise from listening to the proposals of the Spanish governor; and that they even had now a favourable opportunity for obtaining a knowledge of the amount of his force, and for discovering his designs.  For this purpose, therefore, he thought it advisable that they should send an intelligent person, under pretence of congratulating the new governor on his arrival, and thanking him for his offer of amicable terms of peace, who might at the same time gain information of whatever he should consider important to regulate their future conduct.  Caupolican and most of the older officers adopted this judicious proposal, and the important commission was confided to Millalauco, a person who possessed every requisite for the business confided to his charge.