The Spanish conquest of the Inca Empire occurred from 1532 to 1572 when the Spanish Empire conquered the powerful Inca Empire of western South America, leading to the creation of the Viceroyalty of Peru.
The death of the Inca emperor Huayna Capac in 1526 resulted in a civil war between his sons Huascar and Atahualpa, both of whom sought to claim the title of Sapa Inca. The Inca Empire, which stretched from the Patia River in southern Colombia to the Maule River in northern Chile, was home to 16 million people, but most of the empire was ruled by warlords who frequently rebelled against Huayna Capac before his death. Atahualpa controlled the northern regions of the empire while Huascar controlled Cuzco and the area around Lake Titicaca, and Atahualpa was eventually able to capture Huascar during a battle at the gates of Cuzco.
At the same time, the Spanish brothers Francisco, Gonzalo, Juan, and Hernando Pizarro were attracted to South America by rumors of a rich and fabulous kingdom, and, in 1529, Francisco obtained permission from the Spanish monarchy to conquer the land of "Peru". Pizarro and his party of 168 soldiers arrived in Peru in 1532, finding a land devastated by civil war and disease spread by previous Spanish contacts. Pizarro founded San Miguel de Piura in northern Peru before he and his party moved on to the Inca baths at Cajamarca on 15 November 1532, finding Atahualpa there.
The Incas initially believed the Spanish to be gods, and Atahualpa was amazed when Hernando de Soto rode into his camp on a horse. Pizarro denied reports that he and his soldiers had killed and enslaved countless numbers of people on the coast, but, on 16 November 1532, he arranged an ambush at the Cajamarca plaza before his next meeting with Atahualpa. In the ensuing Battle of Cajamarca, the 168 Spaniards overwhelmed Atahualpa's 6,000 unarmed followers, slaying 2,000 Incas with the loss of one soldier wounded. Pizarro allowed Atahualpa's wives to join him before teaching him the game of chess, and Atahualpa was intimidated into ordering his generals Quizquiz and Chalcuchimac to stand down. He later assembled a massive ransom - a room full of gold - which was melted and made into gold bars. Pizarro went on to send out expeditions to Pachacamac and Cuzco, looting Inca towns and capturing Chalcuchimac. After hearing false rumors that Atahualpa had ordered secret attacks on the Spanish, the Spanish executed Atahualpa for polygamy, incestuous marriage, and idolatry even after he agreed to be baptized. The Spanish then installed Tupac Huallpa as their puppet emperor before preparing to finish off the Inca resistance. Shortly after, Pizarro and his 500 soldiers moved toward Cuzco, executing Chalcuchimac after accusing him of secretly communicating with Quizquiz, and they entered the heart of the Tawantinsuyu on 15 November 1533. Not long after, Sebastian de Benalcazar defeated the Incas at Chimborazo in Ecuador and entered Quito shortly after.
Manco Capac II succeeded Tupac Huallpa on the latter's death, and he was initially loyal to the Spanish before his mistreatment by Juan and Gonzalo Pizarro led to his escape from Cuzco and his initiation of an anti-Spanish rebellion. From 1536 to 1537, he led an Inca rebel army to besiege Cuzco, wiping out four relief columns sent from Lima before being forced to lift the siege and withdraw to the fortress of Oliantaytambo. He continued to launch attacks against the Spanish before being forced to retreat to Vilcabamba, where he established the small Neo-Inca State. His son Tupac Amaru I later succeeded him in 1544, but he was killed by the Spanish in 1572, putting an end to the Inca Empire. Meanwhile, Pizarro killed rival conquistador Diego de Almagro in 1541 before being assassinated by Almagro's followers. The Spanish went on to found the city of Lima in 1535 and create the Viceroyalty of Peru, and Viceroy Francisco de Toledo oversaw the conquest of the Neo-Inca State in Vilcabamba. He resettled the Inca in Spanish-style settlements and oversaw increased silver mining at Potosi, using Inca forced labor. The Inca population fell from 12 million in 1520 to less than 3 million by 1570, a decline which continued due to smallpox and measles.