Final answer:
The defeat of the Aztecs by the Spaniards was not due to superior military strategy, but rather to factors like the introduction of diseases, advanced weaponry, and alliances with other indigenous groups.
Step-by-step explanation:
The factor that was not a factor in the defeat of the Aztecs by the Spaniards was superior military strategy. The Spanish did have several advantages such as disease introduction, advanced weaponry, and alliances with other indigenous groups, which contributed to their victory over the Aztec Empire.
Diseases like smallpox decimated the Aztec population at a critical moment, advanced weaponry gave the Spaniards a technological edge in combat, and alliances with indigenous groups like the Totonacs helped to undermine the Aztec Empire from within.