Weeks after Aztec warriors drove Hernán Cortés and his men out of Tenochtitlan in the bloody retreat known as La Noche Triste, the empire's nobles elected Cuitláhuac, brother of the slain Moctezuma II, as the new Tlatoani. His reign proved tragically brief: smallpox, introduced by the Spanish and their allies, was already spreading through the capital and would kill him within months, clearing the way for the empire's final collapse.
The summer of 1520 was catastrophic for the Aztec Empire. Moctezuma II had been killed during the uprising against the occupying Spanish force, and Hernán Cortés's men had fled the capital in the disastrous retreat later called La Noche Triste, losing much of the gold they had looted along the causeways of Lake Texcoco.
Into this vacuum stepped Cuitláhuac, a seasoned military commander and Moctezuma's brother, who had helped organize the resistance that expelled the Spanish. Chosen as Tlatoani around this time, he immediately began rallying the empire's remaining strength, repairing alliances, and preparing Tenochtitlan's defenses for the Spanish return that everyone expected.
But an invisible enemy proved more lethal than Spanish steel. Smallpox, carried by an infected member of a Spanish-allied force, was already tearing through the Valley of Mexico's population, which had no immunity to the disease. Cuitláhuac contracted it and died within roughly 80 days of taking power, one of millions of Indigenous people killed by the epidemic. His successor, the young Cuauhtémoc, inherited a devastated empire that fell to Cortés within a year.
Key people: Cuitláhuac, Hernán Cortés