The Fall of the Aztec Empire — Tenochtitlan starved, besieged, and taken in 1521
On 13 August 1521, after a siege of some three months, the island city of Tenochtitlan — capital of the Mexica and seat of the Aztec Empire — fell, and its last ruler, the tlatoani Cuauhtémoc, was captured trying to escape across Lake Texcoco by canoe. The empire that had dominated central Mexico for nearly a century was broken. The popular image of that conquest — a few hundred Spaniards under Hernán Cortés overthrowing a civilization of millions — is a myth that flatters the conquerors. The fall of Tenochtitlan was achieved by an army that was overwhelmingly Indigenous, fighting alongside a small Spanish contingent, against a Mexica population already devastated by an epidemic the invaders had brought.
The Aztec Empire that fell was a Mexica-led order, the dominant partner in a Triple Alliance with Texcoco and Tlacopan formed around 1428, which extracted tribute from much of central Mexico through war and the threat of war. Tenochtitlan, built on an island in the lake and laced with canals and causeways, was one of the largest cities in the world, with a population estimated in the hundreds of thousands — larger than most European capitals of the age. Its empire was wealthy, sophisticated, and militarily formidable. It was also resented: the peoples it had subjugated and from whom it demanded tribute and captives were, in many cases, willing to ally with anyone who might break Mexica power.
The mechanism of the conquest rested on three pillars, none of them Spanish superiority alone. First and most important were the tens of thousands of Indigenous allies — above all the Tlaxcalans, an independent people the Mexica had never conquered, who supplied the bulk of the fighting force, the local knowledge, the food, and the manpower without which the small Spanish company could not have taken the city. Second was smallpox, introduced by the Europeans in 1520, which swept Tenochtitlan and killed an enormous share of its people — including the ruler Cuitláhuac — gutting the defense before the final siege began. Third was the siege itself: Spanish-built brigantines cut the lake, the causeways were taken block by block, and the aqueduct supplying fresh water was severed, so that the city fell as much to thirst, hunger, and disease as to assault.
The fall of Tenochtitlan inaugurated three centuries of Spanish colonial rule over the heart of Mesoamerica and a demographic catastrophe — driven above all by epidemic disease — that reduced the Indigenous population of central Mexico by perhaps nine-tenths over the following century. Moctezuma II, the ruler when the Spanish arrived, died in Mexica captivity to the invaders in 1520; Cuauhtémoc, who led the final defense, was kept prisoner, tortured for gold, and hanged in 1525. The empire was not so much defeated in a battle as dismantled by alliance, disease, and siege.