The fall of Tenochtitlan, the capital of the Aztec Empire, was a decisive event in the Spanish conquest of the empire. It occurred in 1521 following extensive manipulation of local factions and exploitation of pre-existing political divisions by Spanish conquistador Hernán Cortés.
Although numerous battles were fought between the Aztec Empire and the Spanish-led coalition, which was composed mainly of Tlaxcaltec men, it was the siege of Tenochtitlan that directly led to the downfall of the Aztec civilization and marked the end of the first phase of the Spanish conquest of the Aztec Empire. The Aztec population was devastated at the time by high mortality due to a smallpox epidemic, which killed much of its leadership.
100,000 to 240,000 were killed in the campaign overall including warriors and civilians. As many as 40,000 Aztec bodies were floating in the canals or awaiting burial after the siege. Almost all of the Aztec nobility were dead, and the remaining survivors were mostly young women and very young children. At least 40,000 Aztec civilians were killed and captured.
After the Fall of Tenochtitlan, the remaining Aztec warriors and civilians fled the city as the Spanish allies, primarily the Tlaxcalans, continued to attack even after the surrender, slaughtering thousands of the remaining civilians and looting the city. The survivors marched out of the city for the next three days. One source claims 6,000 were massacred in the town of Ixtapalapa alone. Due to the wholesale slaughter after the campaign and the destruction of Aztec culture some sources have likened the siege to a genocide.
