Pizarro, like all other Europeans, had the distinct advantage of firearms over the indigenous population he sought to subjugate. The Inca hadn't been exposed to gunpowder until the rifles and cannons of the Spaniards were trained on them. And in addition to the actual advantages the gun offered over the spear or the arrow, it also gave the Spaniards a psychological advantage [source: Minnesota State University].
As in Mexico, psychology played a part in the Andes. Montezuma originally mistook Cortés as a returning god; Atahualpa, who had assumed power as the Inca emperor, believed Pizarro and his men were demigods. It was through this initial trust that Pizarro was able to gain Atahualpa's confidence. He soon captured the ruler and held him for ransom.
After he was paid, Pizarro retained the ruler rather than release him. He attempted to use him as a puppet dictator, carrying out the Spaniard's will through the Incan emperor's decrees. But Pizarro found this tactic useless; Atahualpa was executed at the hands of his captor. The blood of thousands more loyal to the Incan ruler was shed soon after.
The brutality of the Spaniards had become apparent to the Inca. Revolts and battles became normal, and to quash these skirmishes, Pizarro used another Cortés tactic: collusion. The conquistador identified tribes who were enemies of the Inca or unhappy with Inca rule, and established alliances with them.
Superior weaponry, psychological warfare, a perfectly timed arrival and native allies certainly helped Pizarro. But remember the Spaniard arrived in the Andes with fewer than 200 men. Even with these advantages, he wouldn't have been successful had it not been for another weapon, unexpected by both sides.
Biological warfare in the form of smallpox allowed Pizarro to conquer the Inca. Smallpox spread quickly through the Americas prior to Pizarro's arrival. Having lived alongside livestock for millennia gave much of Europe immunity to the worst ravages of smallpox. But the indigenous tribes of the Americas had no such advantage.
Smallpox unexpectedly killed Incan emperor Huayna Cupac, leaving the empire in civil unrest and war. The disease decimated the Incan population, paving the way for Pizarro's paltry troops to conquer a once-vast nation. "So complete was the chaos that Francisco Pizarro was able to seize an empire the size of Spain and Italy combined with a force of 168 men," writes Charles Mann in "1491" [source: Mann].
Ultimately, the diseases the Europeans brought with them did more damage than guns or greed. Within the 130 years following Columbus an estimated 95 percent of the Americas' inhabitants died [source: Mann].
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