The Fall of Tenochtitlan, the capital of the Aztec Empire, was a decisive event in the Spanish conquest of the Aztec Empire. It occurred in 1521 following extensive manipulation of local factions and exploitation of pre-existing divisions by Spanish conquistador Hernán Cortés, who was aided by the support of his indigenous allies and his interpreter and companion La Malinche. Although numerous battles were fought between the Aztec Empire under Cuauhtémoc and the Spanish-led coalition, which was itself composed primarily of indigenous (mostly Tlaxcaltec) personnel, it was the siege of Tenochtitlan—its outcome probably largely determined by the effects of a smallpox epidemic (which devastated the Aztec population and dealt a severe blow to the Aztec leadership while leaving an immune Spanish leadership intact)—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.