Hualcopo retired to Riobamba, but there it was impossible to maintain himself, and he was forced to retreat to the fortress of Mocha in the nudo which divides Riobamba from the valley of Latacunga. Here he made a determined and successful stand, and all Tupac's efforts to force his way over the last line of natural fortifications which kept him out of the northern valleys were in vain. The Inca emperor was forced to content himself with assuring his possession of the provinces already conquered. In 1460 he returned to Cuzco, leaving the territory garrisoned. Three years later the heroic Hualcopo died, and was succeeded by his son, Cacha, the fifteenth and last Shiri. The young man signalised his accession to the throne by an aggressive campaign for the recovery of the lost provinces. He passed south into the valley of Riobamba, surprised the Inca garrisons, and put them to the sword, revindicating all the country as far south as the nudo of Azuay. Beyond that range he was unable to go, for all his efforts failed before the obstinate resistance of the inhabitants of Cañar. Tupac began preparations to lead an overwhelming army against Cacha, but his own death interrupted him, and it was not until 1475 that his son, Huaina Capac, surnamed the "great," was able to take the road for the north, determined to put an end to the Shiri dynasty. He first consolidated his power among the tribes on the coast south of Guayaquil, whom his father had left half independent, and then extended his conquests along the northern shore among the barbarians of Manabi. On the island of Puna he put to the sword all the male inhabitants, and one tribe in Manabi, notorious for its abominable and unnatural practices, he extirpated. Returning south, he crossed the mountains in northern Peru, and descending their eastern slopes, waged a bloody war against the Pacamorés, who inhabited the forests where the Upper Amazon debouches into the plain. Having thus secured his line of communications he devoted himself to the main object of the campaign—the conquest of Quito.
Disproportionate as appeared the resources of the contending nations, the war which ensued was well contested. The Caras had resumed their warlike habits and the imminence of the danger animated them and their allies to a desperate resistance. For months the Caras held the great Inca army at bay in the defiles of the Azuay, but finally they were defeated and retreated to the line of Tiocajas. The Incas followed and in a great battle vanquished their opponents so decisively that not only was Riobamba lost, as had happened after the former defeat, but likewise Latacunga and Quito itself. No stand could be made at Mocha, and the Shiri fled to Ibarra, through Quito, where the Caranquis, the most warlike members of the confederacy, were determined to resist to the last. A considerable number of Cara warriors had escaped the slaughter at Tiocajas, and a formidable army assembled to defend the last fortresses in the extreme north of the kingdom. Huaina himself laid siege to Otavalo, the principal stronghold of the Caranquis, but was not able to reduce it. Their successes encouraged them to take the offensive, and in a sortie the Inca emperor narrowly escaped losing his life. Compelled to retire to suppress a mutiny among his southern troops, he left the northern army under the command of his brother, Auqui Toma, and the latter was killed in an assault on the redoubtable fortress of Otavalo. This, however, was the last victory which the Shiri won. Huaina's reinforcements had come up and he advanced with an overwhelming army to avenge his brother's death. Otavalo was taken and its garrison put to the sword; the Shiri fled to another fortress, where he was defeated and slain. The victorious emperor took a fearful vengeance on the Caranquis, whose obstinacy had cost him so dear. Tradition tells that twenty-four thousand were massacred, and their bodies thrown into a lake which has ever since borne the name of Yahuarcocha—the "pool of blood."
Thenceforth the provinces of the old Quito kingdom were integral parts of the Inca empire. The southern valleys had readily accepted the Inca rule, and the central ones appear to have abandoned the Shiri's cause promptly after the second battle of Tiocajas. Though the Caranquis had been exterminated and the Caras had suffered greatly, the other tribes remained intact. The Inca emperor saw that a policy of conciliation would best insure the obedience of these formidable peoples. He spent the remainder of his long life in Ecuador, married the daughter of the dead Shiri, and ruled rather as the legitimate successor of the ancient dynasty than as an alien conqueror. So far as possible the religious, political, and social customs of the Incas were introduced, but it does not appear that the work of amalgamation had proceeded very far in the fifty years which intervened until the advent of the Spaniards. The Quichua had not displaced the native tongues to any great extent, and while the Ecuadorean tribes became loyal subjects, they did not regard themselves as in any way inferior to the older subjects of the empire. Rather had the balance of power passed to them; they had acquired the skill in regular warfare once the exclusive property of the Incas; and the issue of the civil war between Huascar and Atahuallpa seems to prove that they would have played the principal rôle in the Inca system if the advent of the Spaniards had not altered everything.
Huaina Capac died in Quito in 1525, and his body was taken to Cuzco to be laid with his ancestors. In order better to secure the northern kingdom to his descendants he named Atahuallpa, a son by his marriage with the Shiri princess, ruler of the old dominions of Quito. His eldest son, Huascar, was given the rest of the empire with the title of emperor and a suzerainty over Atahuallpa. But Huaina's wise provisions were rendered valueless by the dispute which arose between the two brothers about the boundaries of Atahuallpa's territories. The latter insisted that they included the provinces south of the Azuay, which had been wrested from Hualcopo by Tupac Yupanqui seventy years before, but Huascar would not admit that they extended beyond the hereditary dominions of the Shiri dynasty. The people of Cañar, the most northerly of the disputed provinces, had always been bitter enemies of Quito, and their chief now refused to recognise Atahuallpa as overlord and sent a deputation to Huascar. Atahuallpa despatched his uncle Caluchima and his great general Quizquiz to occupy the province and dethrone the recalcitrant chief. Huascar hurried up some of his Inca regulars to aid the people of Cañar, who won the first battles and advanced towards Atahuallpa's capital. The northerners rallied around the grandson of their old Shiri, and two great armies met on the banks of the Naxichi, only fifty miles south of Quito. Atahuallpa gained a complete victory, and followed it up by advancing over the Azuay into Cañar, where he was again overwhelmingly victorious over a second army which Huascar had sent against him. The whole of southern Ecuador fell into his hands and he took a fearful vengeance on the Cañaris. Atahuallpa himself remained in Ecuador while Quizquiz went on into Peru to achieve that crushing series of victories which resulted in the taking of Cuzco and the capture of Huascar himself. By the year 1532 the whole empire as far south as Cuzco lay prostrate, and it seemed certain that the Cuzco dynasty would be displaced by the illegitimate Quito branch.
