Spanish conquest and Vilcabamba|
Spanish conquistadors led by Francisco Pizarro explored south from Panama, reaching Inca territory by 1526. It was clear that they had reached a wealthy land with prospects of great treasure, and after one more expedition (1529), Pizarro travelled to Spain and received royal approval to conquer the region and be its viceroy.
At the time they returned to Peru, in 1532, a war of succession between Huayna Capac's sons Huascar and Atahualpa and unrest among newly-conquered territories-- and perhaps more importantly, smallpox, which had spread from Central America-- had considerably weakened the empire.
Pizarro did not have a formidable force; with just 180 men, 1 cannon and only 27 horses, he often needed to talk his way out of potential confrontations that could have easily wiped out his party. Their first engagement was the battle of Puná, near present-day Guayaquil, Ecuador; Pizarro then founded the city of Piura in July 1532. Hernando de Soto was sent inland to explore the interior, and returned with an invitation to meet the Inca, Atahualpa, who had defeated his brother in the civil war and was resting at Cajamarca with his army of 80,000 troops.
Pizarro met with the Inca, who had brought only a small retinue, and through interpreters demanded that he convert to Christianity. Atahualpa was handed a Bible and threw it on the floor, which the Spanish interpreted as adequate reason for war, though some chroniclers suggest that Atahualpa simply didn't understand the notion of a book. The Spanish attacked the Inca's retinue (see Battle of Cajamarca), capturing Atahualpa.
Atahualpa offered the Spaniards enough gold to fill the room he was imprisoned in, and twice that amount of silver. The Incas fulfilled this ransom, but Pizarro refused to release the Inca. During Atahualpa's imprisonment Huascar was assassinated. The Spanish maintained that this was at Atahualpa's orders; this was one of the charges used against Atahualpa when the Spanish finally decided to put him to death, in August 1533.
The Spanish installed his brother Manco Inca Yupanqui in power; for some time Manco cooperated with the Spanish, while the Spanish fought to put down resistance in the north. Meanwhile an associate of Pizarro's, Diego de Almagro, attempted to claim Cusco for himself. Manco tried to use this intra-Spanish feud to his advantage, recapturing Cusco (1536), but the Spanish retook the city.
Manco Inca then retreated to the mountains of Vilcabamba, where he and his successors ruled for another 36 years, sometimes raiding the Spanish or inciting revolts against them. In 1572 the last Inca stronghold was discovered, and the last ruler, Túpac Amaru, Manco's son, was captured and executed, bringing the Inca empire to an end.