Castro in Chan Chan
Castro did not intend to follow the steps of previous invaders and try to force the Chancay Road between Saña and Cajamarca. Only Andagoya had succeeded there, and even then at such great cost it had destroyed any hope he had possessed of conquering the Tawantinsuyu. And that had been without the remnants of Quisquis's force organizing a defense in Saña.
Castro used his new laurels to attract more support in his war on the Tawantinsuyu. And he turned south, once again leaving Quisquis in a predicament[1]. Rather then engage in another lengthy chase along the coast Quisquis entered the mountains, hoping to position himself against Castro when the latter turned inland.
Castro's entrance point would end up being the Paramonga River, near the ancient culture in Recauy. The area was not undefended, Atahualpa and his successors were under no illusions that the Spanish would be limited in their attack options, but it was not as greatly fortified as it might have been in better days. Castro's turn inward also had to do with the morale of his men. He was exiting the lands of the Chimu, and he feared desertion if he wandered much longer. In addition his Spanish men were eager to get to some full hearted looting, which had been avoided of late in the name of wooing the Chimu.
Castro would later portray his entry into the mountains as a triumphal march, bringing the cross to the heathen. In reality it consisted of throwing his Chimu allies repeatedly against the Tawantinsuyu defenses. Plague had, of course, weakened their defenses and many soldiers had been siphoned off very recently. Castro had broken into the mountains, and unwittingly stepped into the Civil War.
Ninancoro's Flight was not exactly a poor one.
Just days before Castro emerged, bloodied but victorious, at Recuay Ninancoro had passed by, on his way to Cajacamara. Had he organized the Quitians in the area, as well as those who had spirited him away from Cusco he might have had a chance at retaking the city. But here lay one of the faults of Ninancoro, and an explanation for his apparent lack of desire to be Sapa Inka, he was extremely non-confrontational. "Probably would retake Cusco" was not enough for him, so rather then press Quispe-Tupac he retreated, planning to get a full army to back him. He sent orders to Ukumari in the north to being his army south, and ordered Manco to attack from the desert. Ninancoro planned to meet with Quisquis at Cajacamara to further plan the war.
Had Castro captured Recuay before Ninancoro had fled past it, history would have changed. But he did not. Castro now had two options, a choice that is a useful insight into his objectives. A conquistador seeking only loot would have marched on Cusco, hoping to crush the weak opposition. But Castro wanted to have more then just loot, he wanted power, and for that he need to stop his most dangerous enemies, the Quitians, from assembling. So he turned north, much to the chagrin of some of his greedier followers. But it proved to be the correct one.
Quispe-Tupac was not a fool, despite how some may remember him, the young Sapa Inka realized that on his own he could not defeat his brother's army. The Quitians were the best the Tawantinsuyu had. Cusco was raising an army, but it had fewer experienced soldiers and virtually no modern weapons to speak of. They had seized the main stables of the Royal Family, but all of the rideable horses had been sent to war. Captive Spaniards were also found, but Quisipe-Tupac lacked his father's infamy and the prisoners had their spirits lifted when they had heard rumors of Castro's advance. There was simply no time to match the power the north bore against his empire. Unless…
Unless…
As Castro turned north, hoping to find an agreeable place to face the southern thrust Quisquis would surely be coming, he was pursued. Not by an army, but by messengers. They came from Cusco, bearing gold and silver and promises of more if Castro listened to their plea. Ninancoro's flight to Cajacamara continued unimpeded as Castro listened to the offer.
The Universal Gift Card
Quispe-Tupac's men spun fanciful tales of apology for the "tragic misunderstandings" that had led to the war, pinning the blame on Ninancoro and the Quitians. Yes, the sum Castro demanded was a bit high, but he seemed reasonable enough. Quisipe-Tupac said that he
wanted to pay Castro the money, but claimed that with the civil war he was unable to so. But if Castro were to assist the Cuscan army in defeating the traitors, perhaps some sort of arrangement could be made.
Castro was not a man to be bought off easily, but saw the obvious advantages to be had from the preposition. More troops, experienced with mountain life. Legitimacy for his push to destroy the army of Quitians. Passage and trust in Cusco. And the Sapa Inka delivered into his power. He accepted the offer, and requested Quispe-Tupac join him along with an army and funds. Castro halted his march to see if the young Sapa Inka would join him. His wishes would be granted when, on April 3, the Cuscan Army approached Castro's forces.
Castro received emissaries from Quispe-Tupac, asking that the Spaniard come and see him. Castro asked that the Sapa Inka come see him. Quispe-Tupac would not do it. He was taking a risk as it was to trust Castro, and he would avoid ever leaving his entourage. Eventually Castro relented and visited the young Sapa Inka. The Spaniard was showered in gifts and promised more should victory be achieved. Very little was agreed upon, and less actually understood. For example Quispe-Tupac promised to "raise the cross" in Cusco. Castro took this to be a promise that the empire would convert to Christianity. Quispe-Tupac took it to mean that he would built the Spanish a Church.
But still the armies lumbered north, divided but united in purpose. Quisquis prepared with Ninancoro for the fight of his life. And to the south Manco faced the much awaited Mapuche revolt.
The revolt turned out to be something of an anti-climax. No Toqui ever emerged as a leader of the revolt, and the entire affair was disorganized. Those Mapuche not under Tawantinsuyu rule did little to assist their brethren and the revolt led mostly to more Mapuche being forced across the dessert, bringing news to their exiled cousins. But the revolt had forced Manco to organize all of his forces into one army. And with the Mapuche threat dispersed for now he was free to march north. So he did.
But he did not say whose claim he was supporting.
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1: Poor guy's racking up a bad record ITTL, but IOTL he was one of Atahualpa's finest generals. His defense of Cusco was surprisingly resilient for a man with no Emperor in a hostile land.