Allies and smallpox toppled Tenochtitlan by 1521
Between 1519 and 1521 Hernán Cortés’s small Spanish force plus large Indigenous armies overthrew the Aztec Triple Alliance. Moctezuma’s hegemonic system cracked; smallpox in 1520 killed an estimated five to eight million; Tenochtitlan fell on 13 August 1521.
After Juan de Grijalva’s 1518 Yucatán voyage, Cortés sailed in 1519 against Cuba governor Diego Velázquez’s later recall. He built alliances with tributary altepetl and rivals—above all Tlaxcaltecs and Tetzcocans—plus Cempoala, Huejotzingo, and lakeside polities. The multilingual enslaved woman known as Doña Marina or La Malinche was pivotal as interpreter. Cortés entered Tenochtitlan on 8 November 1519; whether he immediately seized Moctezuma is now doubted by many scholars despite Cortés’s legal claims.
Velázquez sent Pánfilo de Narváez to rein him in. Cortés left Pedro de Alvarado in the capital, beat Narváez on the coast, and absorbed most of that force. Alvarado’s massacre during a religious festival sparked revolt. On the Noche Triste retreat, sources report hundreds of Spaniards and thousands of native allies dead; Moctezuma died under disputed circumstances—Spanish or Indigenous accounts disagree. A year later, famine and disease-weakened Tenochtitlan fell to a Spanish–Tlaxcalan coalition under Cortés and Xicotencatl the Younger, capturing Cuauhtémoc; Mexico City rose on the ruins as New Spain’s capital.
Hassig and Restall argue guns, steel, horses, and dogs helped a few hundred Spaniards survive but did not alone explain empire-scale victory; Indigenous manpower, local geography, and timing did. Aztec rule through local elites depended on prestige that moderate shocks could shatter. Cavalry mattered in battle, yet Restall calls Spanish arms a formula for survival until reinforcements arrived. Many on the 1519 entrada, including Cortés, had never seen combat; Caribbean precedents still shaped tactics such as seizing caciques.
The Triple Alliance of Tenochtitlan, Texcoco, and Tlacopan dated to 1428; Moctezuma II became huey tlatoani in 1502. Within three years of Cortés’s landing, Mesoamerica’s strongest pre-Columbian empire was a Spanish viceroyalty’s foundation.
Source: Spanish conquest of the Aztec Empire
