The Aztec Empire fell to the Spanish in 1521, when Spanish-led forces captured Tenochtitlan, the Mexica capital. The decisive siege lasted from May 26 to August 13, 1521, and ended with the surrender of the ruler Cuauhtémoc.
The conquest was not a victory achieved by Spaniards alone. Hernán Cortés commanded a coalition that included thousands of Indigenous allies, especially warriors from Tlaxcala and other enemies or tributaries of the Mexica. The Spanish also used brigantines on Lake Texcoco to cut off the island city’s causeways, supplies, and escape routes.
Disease, particularly smallpox, had already devastated the population and weakened Mexica leadership before the final siege. After the city’s fall, much of Tenochtitlan was destroyed, and Spanish authorities began building Mexico City as the center of New Spain. The date 1519 is sometimes confused with the empire’s fall because Cortés arrived on the Mexican coast that year, but the conquest concluded two years later, in 1521.