Much gratified with the prosperous issue of his voyage, the zealous missionary returned to Chili in 1612, carrying a letter written by the king of Spain to the national assembly of the Araucanian chiefs, recommending the establishment of peace between the nations, and that they should promote the propagation of Christianity among their dependents. Immediately on his arrival in Chili, Valdivia hastened to the frontiers, and communicated the nature of the commission with which he was entrusted to the Araucanians, by means of some prisoners of that nation whom he had purposely brought with him from Peru. Aillavilu the toqui gave little attention to the proposed negociation, which he deemed a feint for deceiving and surprising him. But, as he died or resigned the command soon after, his successor Ancanamon thought proper to inquire into the reality of the pacific proposals, and directed the ulmen Carampangui to converse with Valdivia, that his offers might be laid before a general assembly of the ulmens. Accordingly, on the invitation of Carampangui, Valdivia repaired to Nancu in the province of Catiray, where, in an assembly of fifty Araucanian chiefs, he made known the substance of the proposed pacific negociations, read and expounded the royal letter to the Araucanian confederacy, and made a long oration on the motives of his interference and on the important concerns of their immortal souls. The assembly thanked him for his exertions, and promised to make a favourable report to the toqui. On his return to Conception, Valdivia was accompanied by Carampangui, where he was honourably received by the governor; who dispatched Pedro Melendez one of his ensigns, under the safeguard of the ulmen, on a message to the toqui, carrying with him the letter of the king of Spain, and a request that Ancanamon would meet him at Paicavi, a place near the frontiers, that they might confer together upon the preliminaries of peace.
The toqui soon afterwards came to the place appointed, with a small guard of forty soldiers, and accompanied by several ulmens, bringing likewise along with him a number of Spanish prisoners of the first families, whom he set at liberty. The governor, with Valdivia and the principal officers of the government, received Ancanamon with every demonstration of respect, and conducted him to the lodgings appointed for his reception amid the repeated discharges of artillery. The governor then proposed, as preliminary articles of peace, that the river Biobio should serve hereafter as the common boundary between the Spanish and Araucanian nations, beyond which neither should be permitted to pass with an army: That all deserters should in future be mutually returned: And that missionaries should be allowed to preach the doctrines of Christianity in the Araucanian territories. Ancanamon required as a preliminary, that the forts of Paicavi and Arauco, which had been lately erected upon the sea coast to the south of the Biobio, should be evacuated. The governor immediately abandoned Paicavi, and agreed to give up the other immediately after the conclusion of peace. Being so far agreed, and as the consent of the four toquis of the uthalmapus was requisite to ratify the treaty, Ancanamon proposed to seek for them in person, and to bring them to the Spanish camp.
While the negociation was in this state of forwardness, an unlooked for event rendered all these pacific measures abortive. Ancanamon had a Spanish lady among his wives, who, taking advantage of his absence, fled for refuge to the governor, accompanied by four other women who were wives to the toqui, and two young girls his daughters. The toqui was extremely indignant on this occasion, though less exasperated by the flight of his wives, than by the kind reception they had experienced among the Spaniards. Relinquishing every thought of peace, he immediately returned to the governor, from whom he demanded the restitution of the fugitives. His demand was taken into consideration by a council of the officers; but the majority of these, many of whom were averse to peace, refused to surrender the women to the toqui, alleging that they were unwilling to expose them to the danger of relapsing from the Christian faith which they had embraced. After many ineffectual propositions, Ancanamon consented to limit his demands to the restitution of his daughters, whom he tenderly loved. To this it was answered, that as the eldest had not yet embraced the Christian faith, his request respecting her would be complied with, but as the younger had been already baptised, they could not think of delivering her into his hands.
At this time the almost extinguished hopes of peace were revived for a time by an unexpected incident. Utiflame, the apo-ulmen of Ilicura near Imperial, had always been among the most inveterate enemies of the Spaniards, and to avoid all intercourse with them, had constantly refused to ransom his sons or relations who happened to be made prisoners. He prided himself on having so successfully opposed all the Spanish governors of Chili, from the elder Villagran to Rivera, that the enemy had never been able to acquire a footing in his province, though near the city of Imperial. One of his sons who had been taken in the late war, was about this time sent back to him by Valdivia, in consequence of which he was so highly gratified, that he went immediately to visit the missionary at the fort of Arauco, where in return for the civilities he experienced from the governor and Valdivia, he engaged to receive the missionaries into his province, and to use his influence with Ancanamon to conclude a peace with the Spaniards. He observed, however, that it was necessary in the first place to restore his women, which could be done with safety by obtaining in the first place a safe conduct from the toqui, and undertook to manage the business. He accordingly departed from Arauco for Ilicura, accompanied by three missionaries, one of whom was Horatio Vecchio, the cousin of Pope Alexander VII. The exasperated toqui no sooner learnt the arrival of the missionaries at Ilicura, than he hastened to that place with two hundred horse, and slew them all with their defender Utiflame. Thus were all the plans of pacification rendered abortive, though Valdivia used repeated attempts to revive the negociation. All his schemes were disconcerted by the contrivances of the officers and soldiers, who were interested in the continuance of the war, and loudly demanded that vengeance should be taken for the blood of the slaughtered priests. Notwithstanding his anxious desire for peace and the pious intentions of the king, the governor found himself compelled to prosecute the war, which was renewed with more fury than ever. Ancanamon the toqui, being eager to revenge the affront he had received in regard to his women, incessantly harassed the southern provinces of Spanish Chili, and his successor Loncothegua continued hostilities with equal obstinacy; but only very imperfect accounts of this period of the war have been given by the contemporary historians. The governor Rivera died at Conception in 1617, having appointed as his successor Fernando Talaverano the senior oydor of the royal court; who was succeeded ten months afterwards by Lope de Ulloa.
The toqui Loncothegua resigned in 1618, and was succeeded in the supreme command of the Araucanian armies by an officer named Lientur, whose military expeditions were always so rapid and unexpected, that the Spaniards used to call him the wizard. All his designs were perfectly seconded by Levipillan, his vice toqui. Though the line of the Biobio was amply secured by fortresses and centinels, these indefatigable enemies always contrived to pass and repass without experiencing any material loss. The first enterprise of Lientur was the capture of a convoy of four hundred horses, which were intended to remount the Spanish cavalry. He next ravaged the province of Chilian, and slew the corregidor with two of his sons and several of the magistrates, who had attempted to resist him in the field. Five days afterwards, he proceeded towards St. Philip of Austria, otherwise called Yumbel, a place about sixty miles to the east of Conception, with six hundred infantry and four hundred horse, all of whom he sent out in various detachments to ravage the surrounding country, leaving only two hundred men to guard the narrow defile of Congrejeras. Provoked at this daring enterprise, Robolledo, the commandant of Yumbel, sent seventy horse to take possession of the pass and cut off the retreat of the toqui; but they were received with such bravery by the Araucanian detachment, that they were compelled to retire for security to a neighbouring hill, after losing their captain and eighteen of their number. Robolledo sent three companies of infantry and all the rest of his cavalry to their aid; but Lientur who had by this time collected all his troops together, fell upon the Spaniards, notwithstanding the continual fire of their musquetry, and put their cavalry to flight at the first charge. The infantry, thus left exposed, were almost all cut to pieces, thirty-six of them only being made prisoners, who were distributed among the several provinces of the Arancanian confederacy. If Lientur had then invested Yumbel it must have fallen into his hands; but he deferred the siege till the following year, when his attempt was rendered unsuccessful by the valiant defence of Ximenes who then had the command. On his repulse however, he assaulted and took a fort named Neculgueno, the garrison of which was put to the sword, and all the auxiliaries who dwelt in that neighbourhood were made prisoners. Lientur followed up these successful exploits with others equally fortunate, which are not particularized by contemporary writers, who have given him the title of the darling of fortune.