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.

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.

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 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.

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.

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.

Despite being hardened by years of brutal warfare, figures like Diego de Almagro and Manco Inca repeatedly made fatal errors by naively trusting their Spanish rivals. Almagro released hostages on a flimsy promise, and Manco sheltered his own assassins, showcasing a recurring, fatal gullibility.

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.