Final answer:
The Spanish were able to defeat the Aztecs due to factors such as superior military tactics and weaponry, alliances with native tribes, and the inadvertent introduction of smallpox. By playing upon the disunity among the diverse groups in the Aztec Empire, the Spanish were able to capture Tenochtitlan.
Step-by-step explanation:
The Spanish were able to defeat the Aztecs due to a combination of factors. Firstly, the Spanish had superior military tactics and weaponry, such as steel armor, swords, and the ability to attack on horseback. The Aztecs, on the other hand, fought with bows and arrows and spears. Additionally, the Spanish found unexpected allies in tribes that had been forced to pay tribute to the Aztec Empire, such as the Totonacs.
Furthermore, the inadvertent introduction of smallpox into Tenochtitlan resulted in the deaths of thousands, weakening the Aztecs. The Spanish also took advantage of the disunity among the diverse groups in the Aztec Empire, establishing alliances with native peoples who resented Aztec rule. Through these factors, Cortés and his small force were able to defeat the Aztecs and capture Tenochtitlan.