The Spanish were a tiny fraction of their own fighting forces. Their victory was a political achievement, leveraging deep-seated resentments of subjugated peoples against the Aztec and Inca empires, turning local populations into the primary military asset.

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.

Focused on winning his civil war, Atahualpa fatally misjudged the Spanish. He saw the small group as a potential asset—a source of mercenaries, horses, and superior swords to be captured and repurposed. He never considered them an existential threat to his empire, which sealed his fate.

The conflict was defined by three fracture lines: Spanish-Inca, intra-Inca, and intra-Spanish. The vicious rivalry between the Pizarro and Almagro factions created a power vacuum and chaos that both fueled and complicated the Inca uprising, making it the most dangerous factor.

The Spanish conquest was an iterative process. Pizarro explicitly learned from and followed Cortés's playbook a decade later. In contrast, the Inca likely didn't even know the Aztecs existed. Europeans operated within a connected world, accumulating knowledge, while American empires were informationally isolated and vulnerable to repeated strategies.

The narrative of a small Spanish force conquering a vast empire is misleading. The Spanish heavily relied on indigenous allies, like the puppet emperor Paolo Inca, who provided thousands of warriors. These alliances were decisive in key battles, revealing the conquest was also a native civil war exploited by Europeans.

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.

Atahualpa prioritized defeating his brother Huascar over addressing the existential threat of the Spanish. He viewed the conquistadors as a temporary factor to be managed, not a permanent invading force, a miscalculation that cost him his empire and his life.

The Spanish conquest was plagued by intense internal rivalries. The promise of gold in Quito sparked a race between three separate Spanish expeditions, led by Benalcátha, Almagro, and Pedro de Alvarado. This competition nearly erupted into open warfare, showing how the lure of wealth fractured the invading force.