Mexican Smallpox Epidemic

Timeline

1. 1520Cempoala · VeracruzCuban governor Velázquez sent Narváez to Mexico to arrest Cortés. The fleet carried at least one active smallpox case, and the disease took hold among indigenous people around Cempoala. Traditional accounts may attribute the spread to the African slave Francisco de Eguía accompanying the army; details remain disputed.
2. 1520Valley of Mexico · Valley of MexicoSmallpox spread slowly inland from May to September, passing through Tepeaca, Tlaxcala, and other places, entering Tenochtitlan around autumn. By then the Spanish had withdrawn to Tlaxcala after the Noche Triste, and the disease spread independently among a population with no immunity.
3. 1520Tenochtitlan · Valley of MexicoIn autumn the city saw high fevers, rashes, and mass deaths; the sick could not eat or care for their families, and corpses piled up. Cuitláhuac, who governed after Montezuma, died of pustular disease after a reign of only about eighty days, and Cuauhtémoc succeeded him. The Nahuatl chronicle states he died at the end of the month Quecholli.
4. 1521Tenochtitlan · Valley of MexicoAfter the first peak, the capital's population, warriors, and local rulers suffered heavy losses, and the alliance's mobilization capacity declined. While Cortés reorganized his forces in Tlaxcala, the Aztec side was still dealing with the epidemic's aftermath. The epidemic thus became a key variable before the 1521 siege, rather than the siege itself.