Cortés and his allies landed their forces in the south of the island and fought their way through the city, street by street, and house by house. Though better armed, the Spanish still suffered reverses. Gradually, the whole southern part of the island, the original city of Tenochtitlán, fell to the Spanish. The defenders, who were estimated at 300,000, became concentrated in the northern part of island, where they fought for 80 days.

When a guiding omen confirmed that defeat was inevitable, the Aztec leaders gathered to discuss what to do, how best to surrender, and "what tribute to pay." Cuatemoc was led to Cortés. "Cortés stared at him for a moment and then patted him on the head." The meaning of this apparently demeaning gesture seems to be revealed in the account of Alva Ixtilxochitl, a descendant of one of the allied kings who fought for Cortés. "Cortés received him with all the respect due to a king. Cuautemoc then asked Cortés to kill him: 'For you have already destroyed my city and killed my people.'" The same day as the surrender, the Spanish looted the city while their native allies ran amok, taking revenge against their ancient tormentors. Many people fled to the mainland by canoe in daytime, most by night, "crashing into each other in their haste."