The Pizarro brothers' extreme degradation of Manco—urinating on him while chained—was intended to break him. Instead, it became an unforgivable act of psychological warfare that backfired, destroying any chance of a puppet regime and fueling an all-out war of resistance.

The small Spanish force could not have survived the siege of Cusco or conquered the empire alone. They relied critically on thousands of native auxiliaries from rival ethnic groups, as well as Inca nobles who opposed Emperor Manco, turning the conflict into a multi-sided civil war.

Despite commanding armies of tens of thousands, Inca generals were so disoriented by the unheard-of capture of their divine emperor that they offered no resistance. This complete bewilderment allowed a handful of Spaniards to dictate terms to a vastly superior force.

The Spanish didn't defeat the Inca Empire at its height. They arrived after a smallpox epidemic killed the emperor and a subsequent brutal civil war between his sons shattered the empire. This left the civilization politically fractured and militarily exhausted, making it ripe for conquest by a small force.

The absolute divine authority of the Sapa Inca meant that capturing a single man, Atahualpa, effectively paralyzed a 12-million-person empire. With no alternative power structure, his generals were bewildered and leaderless, allowing a tiny Spanish force to maintain control.

Manco first viewed the small Spanish force as mercenaries he could leverage to restore order and his own authority after the devastating Inca civil war, completely underestimating their ultimate colonial ambitions and disruptive potential.

To escape Cusco and launch his rebellion, Manco exploited his captor Hernando Pizarro's insatiable greed. He claimed he needed to leave the city to retrieve a massive golden statue of his father. Pizarro, blinded by the prospect of treasure, readily believed the lie and let him go.

The Pizarro brothers, Juan and Gonzalo, relentlessly humiliated Emperor Manco by abducting and abusing his wife and sister. This personal cruelty, driven by lust and arrogance, directly sabotaged their fragile alliance and incited the devastating siege of Cusco.

The Spanish conquest of the Incas succeeded largely because they inserted themselves into an existing civil war. By siding with the southern Inca faction against the northern one, they gained crucial local allies, transforming the conflict from a foreign invasion into a complex, multi-sided war they could manipulate.