He now dispatched Aguirre, with 200 men to conquer Cuyo and Tucuman, and returning with fresh troops into Araucania, he built the city of La Frontera; and having effected this object, retired to Concepcion, and dispatched a messenger to Spain, with an account of his conquests, a solicitation of the government, and of the title of Marquess del Arauco, and he sent Francisco de Ulloa by sea, to explore the Straits of Magellan, by which he hoped to carry on a communication with the mother-country, independent of Peru. Occupied with these affairs, he did not perceive the increasing power of the Araucanians, who having deposed Lincoyan, elected _Caupolican_, a warlike chief, to the supreme command of their army. Caupolican then attacked the fort of Arauco, which the Spaniards abandoned in the night; he also compelled them to evacuate Tucapel, both of which he destroyed. Valdivia immediately collected what force he could, marched against him, but sending an advanced guard of ten horsemen to reconnoitre, they were cut off, and their heads fixed in the road through which the Spanish army was to pass. This army arrived in sight of the Araucanians, on the 3d of December, 1553, when a fierce contest immediately commenced. The Araucanians were put to flight, but in their confusion, a young chief who had been baptized and employed as page to Valdivia, suddenly deserted the Spanish army, and brandishing a lance, called out to his countrymen to turn and follow his example; this so encouraged the enemy, that they immediately commenced a fresh attack, with such success, that the Spaniards and their Promaucian allies were cut to pieces, only two of the latter escaping. Valdivia retired with his chaplain to a convenient spot, and having received absolution, prepared himself for death. He was soon taken prisoner, and his late page, begging that he might be spared, was on the point of obtaining his release, when an old Ulmen, indignant at the fate of his countrymen who had fallen in the battle, put an end to the conference, and the existence of Valdivia by a blow with his war-club. On the news of the defeat and death of the governor arriving at Concepcion, Villagran was appointed to the chief command, and marching with a force against the Araucanians, he was defeated by _Lautaro_, the page before mentioned, and losing 700 men, was forced to retreat to Concepcion, which place he abandoned and proceeded to St. Jago. By his wise measures and resolute conduct, as well as by the dreadful ravages of the small-pox which had been communicated to the Araucanians, the Spanish possessions were once more established, but battles were constantly fought between the natives and the settlers, which though they generally terminated in favour of the Europeans, were the means of their losing many settlements, and Lautaro the toqui, was slain in 1556, in an action with Villagran.