Early firearms inflicted minor physical damage, but the psychological impact was immense. To the Inca, who had never heard gunpowder, the Spanish appeared to control thunder. This shock, combined with cavalry, induced panic and collapse in veteran armies, creating lopsided victories with near-zero Spanish casualties.

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 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 Aztecs' and Incas' centralized, hierarchical structure was their greatest vulnerability. By capturing a single leader—the emperor—the Spanish could destabilize or control the entire system. In contrast, dispersed peoples like the Maya required a long, grinding war of attrition to subdue.

Once easily accessible gold was gone, the Spanish conquest of Peru transitioned from looting to institutionalized exploitation. Pizarro began granting `encomiendas`—huge tracts of land with thousands of indigenous laborers. This shifted the economic model from a short-term gold heist to a long-term colonial system based on forced tribute.

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 Spanish forces were so confident in their advantage that they fought civil wars among themselves while actively conquering empires of millions. This reveals they didn't see the natives as a true existential threat, a fatal miscalculation by Aztec and Inca leaders who failed to exploit these divisions.

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.

Francisco Pizarro's invasion of Peru was heavily influenced by the recent success of his cousin, Hernán Cortés, in Mexico. The fall of the Aztecs provided a tangible model for conquest, proving that small bands of conquistadors could topple vast empires. This precedent made it easier for Pizarro to secure funding and royal support.