On what exact date did Tenochtitlan surrender to the Spanish?

Tenochtitlan surrendered to the Spanish on August 13, 1521. The date is commonly given in the Julian calendar used in the Spanish world at the time; the corresponding date in the modern Gregorian calendar is August 23, 1521.

The surrender followed an 80-day siege led by Hernán Cortés and supported by tens of thousands of Indigenous allies, especially from Tlaxcala and Tetzcoco. Spanish forces used brigantines on Lake Texcoco to sever the city’s access to food, water, and reinforcements. Fighting devastated both Tenochtitlan and neighboring Tlatelolco.

Cuauhtémoc, the Mexica ruler, was captured while attempting to flee by canoe and surrendered to Cortés. The conquest was not simply a Spanish victory over the Aztecs: Indigenous enemies of Mexica imperial rule supplied most of the allied military force. The fall marked the destruction of the Mexica capital and the foundation of Spanish colonial rule in central Mexico.