The Siege of Cuzco was the siege of the city of Cusco by the army of Sapa Inca Manco Inca Yupanqui against a garrison of Spanish conquistadors and Indian auxiliaries led by Hernando Pizarro in the hope to restore the Inca Empire. A setback in the Spanish conquest of the Inca Empire, the siege lasted ten months but was ultimately unsuccessful.
During the Siege, Pizarro succesfully recruited a wealthy councillor of Manco, Tuti Cusi, who was tasked to plan an attempt on his Emperor's life. However, the traitor's plan failed with Manco being saved by Assassin Gonzalo Pardo and Quila.
A Spanish expedition led by Francisco Pizarro had captured the Inca capital of Cuzco on November 15, 1533 after defeating an Inca army headed by general Quisquis. The following month, the conquistadors supported the coronation of Manco Inca as Inca emperor to facilitate their control over the empire. Real power rested with the Spaniards who frequently humiliated Manco Inca and imprisoned him after an attempted escape in November 1535. After his release in January 1536, Manco Inca left Cuzco on April 18 promising the Spanish commander, Hernando Pizarro, to bring back a large gold statue when in fact he was already preparing a rebellion.
Having realized their mistake, Hernando Pizarro led an expedition against Manco Inca's troops, which had gathered in the nearby Yucay Valley; the attack failed as the Spaniards had severely underestimated the size of the Inca army. The Inca emperor did not attack Cuzco at once, instead he waited to assemble his full army estimated at between 100,000 and 200,000 men strong around the city, against them there were 190 Spaniards (80 of them horsemen) and several thousand Indian auxiliaries.
The siege started on May 6, 1536 with a full-scale attack towards the main square of the city; the Inca army succeeded in capturing most of the city while the Spaniards took refuge in two large buildings near the main plaza. The conquistadors fended off Inca attacks from these constructions and mounted frequent raids against their besiegers.
After 10 months of vicious fighting in Cuzco, with low morale playing a factor, Manco Inca decided to raise the siege at Cuzco and withdraw to Ollantaytambo and then Vilcabamba, where he established the small Neo-Inca State. It is suggested by some that by this action he threw away his only real chance to rebuff the Spaniards from the lands of the Inca Empire, but it was probably the only realistic choice he had considering the arrival of Spanish reinforcements from Chile led by Diego de Almagro. Upon facing victory and the availability of expanding his own reign into Peru, Almagro seized the city once having achieved victory for Spain and had Hernando and Gonzalo imprisoned. Gonzalo escaped, to later face Almagro in a personal triumph at the Battle of Las Salinas.