In the spring of 1536, one of the most dramatic military confrontations of the Spanish conquest of the Americas began in the highlands of Peru. The siege of Cusco, which lasted ten months and pitted a massive Inca army against a small but determined garrison of Spanish conquistadors, represented the most serious challenge the nascent colonial regime would face. Its outcome would shape the history of the continent for generations.
The roots of the siege stretched back to the rapid and often brutal series of events that had unraveled the Inca Empire in the years following Francisco Pizarro's arrival in Peru. Armed with a royal grant known as the Capitulation of July 1529, in which King Charles I of Spain bestowed on Pizarro the rights of discovery and conquest over Peru, or New Castile, along with the governorship of the territory, Pizarro had advanced into the Andean heartland with a force that was small in number but devastating in impact. On 16 November 1532, at Cajamarca, Pizarro's men captured the Sapa Inca Atahualpa in a surprise assault that killed thousands of his attendants and left the empire's supreme ruler a prisoner.
Atahualpa's capture sent shockwaves through Inca society. Hoping to secure his release, the emperor organized a ransom of staggering proportions, ultimately delivering over 39,000 pounds of gold and silver to the Spaniards. Despite receiving the ransom, the conquistadors executed Atahualpa in July 1533. His death intensified pre-existing rivalries for the Inca throne, fracturing the empire along lines of dynastic competition that the Spanish were quick to exploit.
Pizarro installed a succession of puppet rulers in an attempt to govern through Inca legitimacy while keeping real power in Spanish hands. He appointed Tupac Hualpa, a brother and rival of Atahualpa, as Sapa Inca in September 1533, but Tupac Hualpa was murdered by Chalcuchima, a loyalist military commander of Atahualpa's faction. Pizarro then turned to Manco Inca, another brother of Atahualpa and son of the last truly unified ruler, Huayna Capac. Pizarro had first encountered Manco during the Spanish march on Cusco, and he calculated that installing Manco would deepen internal Inca divisions. Manco, for his part, initially allied with the Spaniards to strengthen his position in the ongoing dynastic struggle.
The Spanish captured the Inca capital of Cusco on 15 November 1533 after defeating an Inca army under the general Quisquis. The following month, they sponsored the official coronation of Manco Inca as emperor, an act designed to give the colonial arrangement a veneer of indigenous legitimacy. But real authority belonged to the Spaniards, and Manco's position as a figurehead was humiliating. The brothers Juan Pizarro and Gonzalo Pizarro, younger siblings of Francisco, exercised direct control over the city and treated Manco with contempt. Juan Pizarro imprisoned Manco after he attempted to escape in November 1535.
Hernando Pizarro, yet another of Francisco's brothers, returned from Spain and assumed command of Cusco. Hoping to improve relations and secure Manco's cooperation, Hernando released him from confinement in January 1536. Manco was granted greater freedom of movement, though still under Spanish supervision. He used this freedom with cold calculation. On 18 April 1536, he obtained Hernando Pizarro's permission to travel to the Yucay Valley ostensibly to perform religious ceremonies and gather gold. Instead, Manco went to Lares and convened a war council with Inca military chiefs, sealing his rebellion over cups of ceremonial chicha. He had assembled an army estimated by various sources at between 40,000 and 200,000 warriors, a force that dwarfed anything the Spaniards could muster.
The siege formally began on 6 May 1536. Hernando, realizing his catastrophic error, dispatched Juan Pizarro with seventy cavalrymen to disperse the Inca forces gathering in the Yucay Valley. Juan's expedition found and cleared the valley after a brief skirmish, but word soon arrived that Inca forces had encircled Cusco entirely. The city held only 190 Spanish soldiers, of whom 80 were mounted cavalrymen, supported by Indian auxiliaries.
The Inca forces moved to seize the fortress of Sacsayhuamán, a massive stone complex overlooking Cusco that, if held by the attackers, would give them an overwhelming strategic advantage. In a desperate assault, Juan Pizarro led a night attack on the fortress. He was killed during the assault, struck on the head with a stone since he had removed his helmet to see better in the darkness. Despite his death, the Spaniards took the fortress, denying Manco a platform from which to destroy the city below.
For months, the siege continued. The Inca forces set fire to Cusco's thatched roofs, and much of the city burned. Spanish cavalry made repeated sorties against the surrounding forces, exploiting the open terrain where horses gave them a decisive advantage. Manco's forces controlled the surrounding countryside and cut off supply lines, but the garrison held on with grim determination. Relief columns sent from the coast by Francisco Pizarro were ambushed and destroyed, deepening the isolation of the besieged men.
By March 1537, with no decisive breakthrough achieved, the siege collapsed. The Inca army was needed elsewhere, and the agricultural cycle demanded the return of many warriors to their fields. Manco withdrew to the jungle region of Vilcabamba, where he established a rump Inca state that would persist for several more decades. The siege of Cusco was the best opportunity the Incas ever had to expel the conquistadors, and its failure ensured that Spanish power in the Andes would endure.
