The Spanish conquest of the Aztec Empire really does seem like one of the most improbable events in history. Starting with just over five hundred soldiers, Hernán Cortés was able to defeat a massive force with hundreds of thousands of warriors. There were several factors on the side of the Spanish that helped them achieve this feat.

First of all, the Aztecs did not immediately recognize the Spanish to be the threat that they were. King Montezuma II was cautious, but he was also curious. Montezuma allowed the Spaniards into the city of Tenochtitlan to learn more about them. There are some accounts, however, that claim that this was done to entrap Cortés and his men. Either way, Cortés took advantage of this and captured the Aztec king, making him their hostage and puppet. This situation soon destroyed the Aztecs' faith in their leader, and according to the Spanish, Montezuma was killed by his own people. As such, the Aztecs found themselves leaderless and subsequently more vulnerable.

Another factor working in the favor of the Spanish was Cortés' ability to assess the political climate in Mexico and make convenient allies. The Aztecs were not thought of fondly by their neighbors who were forced to pay them large tributes in order to keep the peace. Cortés won these people over through gifts and promises. He was able to gain valuable intelligence about the Aztecs this way and soon amassed a force of other Mexican peoples to accompany him as he marched towards the Aztec capital. The Tlaxcaltecs, in particular, sent many of their soldiers to join Cortés' force.

Despite all this, the Spanish were forced to flee Tenochtitlan on the night of June 30, 1520. Cortés regrouped and returned with more Spanish and indigenous reinforcements which allowed him to definitively take control of the Aztec capital after a long siege.