The Aztec Empire fell on August 13, 1521, when the Spanish conquistador Hernán Cortés and his indigenous allies captured the Aztec capital, Tenochtitlán. The fall followed a 93-day siege during which the Spanish and their allies gradually wore down the Aztec defenders, ultimately breaking through the city's defenses, leading to the city's sack and the capture of the Aztec emperor Cuauhtémoc. This event marked the rapid collapse of the Aztec Empire and the beginning of Spanish colonial rule in the region.