The Fall of Tenochtitlán: Cortés, Smallpox, and the End of the Aztec World

# The Fall of Tenochtitlán: Cortés, Smallpox, and the End of the Aztec World

In November 1519, Hernán Cortés and approximately 400 Spanish soldiers, accompanied by
several hundred Cuban auxiliaries, entered the Aztec capital of Tenochtitlán as guests of
the emperor Moctezuma II. What they found astonished them. Tenochtitlán, built on an island
in Lake Texcoco where modern Mexico City now stands, was one of the largest cities in the
world at the time — a metropolis of perhaps 200,000 to 300,000 inhabitants, connected to
the mainland by great causeways and fed by an elaborate system of chinampas, the floating
gardens that made the lake basin extraordinarily productive. The Spanish had never seen
anything like it. Within two years, it lay in rubble, and the political and cultural world
it represented was destroyed. The conquest of Mexico is one of history's most consequential
events, and also one of the most complex to analyze and understand.

## The Aztec Empire at Its Height

The Triple Alliance — the Aztec political confederation formed by Tenochtitlán, Texcoco,
and Tlacopan in 1428 — had expanded through military conquest to control a network of
tribute-paying states that stretched from the Gulf Coast to the Pacific and from central
Mexico southward into what is now Guatemala. The empire extracted tribute in the form of
food, textiles, precious stones, feathers, and human captives for ritual sacrifice from
dozens of subject peoples. This tribute system sustained the ruling class of Tenochtitlán
and funded the construction of the great temples and infrastructure of the capital.

But the tribute system also generated enemies. Many subject peoples resented the demands
of Aztec overlordship and the constant need to supply captives for sacrifice. The Tlaxcalans,
an independent confederation that had successfully resisted Aztec conquest, were particularly
bitter rivals. When Cortés arrived on the Gulf Coast in 1519 and began moving inland, he
was entering a political landscape divided and resentful in ways that a purely military
analysis could not have predicted.

## Cortés's Gambit and the Alliance with Tlaxcala

Cortés' strategic genius — and his profound ruthlessness — lay in his recognition that
Spanish military technology alone, while significant, was insufficient to conquer a major
empire. His small force of 400 Spaniards could not have taken Tenochtitlán against a united
opposition. What Cortés did was transform a military expedition into a political one. By
defeating and then negotiating with the Tlaxcalans, he converted a potentially devastating
enemy into an indispensable ally. Tens of thousands of Tlaxcalan warriors would fight
alongside the Spanish in the final siege of Tenochtitlán, motivated not by loyalty to
Spain but by hatred of the Aztec overlords who had imposed tribute and supplied the
sacrificial victims for Tenochtitlán's temples.

The entry into Tenochtitlán as guests of Moctezuma was followed by the Spanish seizure
of the emperor himself as a hostage — a move of stunning audacity that temporarily
paralyzed Aztec political response. When Moctezuma died in disputed circumstances in June
1520 and the Spanish were driven from the city in the bloody retreat known as La Noche Triste,
Cortés lost perhaps two-thirds of his Spanish force. That he recovered and returned to
besiege the city was a testament both to his personal determination and to the enormous
military contribution of his indigenous allies.

## Smallpox: The Invisible Conqueror

No account of the conquest can omit the role of epidemic disease, and specifically of
smallpox. The Variola major virus, to which indigenous Americans had no prior exposure
and therefore no immunity, preceded the final Spanish assault on Tenochtitlán. An outbreak
in 1520, estimated by historians to have killed 25 to 50 percent of the city's population
within months, killed Cuitláhuac, the Aztec ruler who had organized the expulsion of the
Spanish during La Noche Triste. It killed warriors, administrators, farmers, and nobles
indiscriminately. When the Spanish and their Tlaxcalan allies besieged Tenochtitlán in
May 1521, they were besieging a city already devastated by epidemic. The 75-day siege that
ended in August 1521 with the capture of the final emperor Cuauhtémoc was fought against
a defense that smallpox had already broken.

## The Colonial Aftermath and Population Collapse

The decades following 1521 saw a population collapse in central Mexico that dwarfs even
the Black Death in proportional terms. Demographic historians estimate that the indigenous
population of central Mexico — perhaps 25 million in 1519 — had declined to approximately
1 million by 1600. Smallpox was the principal killer, but it was followed by measles,
typhus, influenza, and a series of epidemic waves throughout the sixteenth century. The
colonial labor system imposed by Spain — the encomienda, through which Spanish settlers
received the labor of indigenous communities — extracted work from a population already
devastated by disease. Silver mining in particular, at Potosí in Peru and Zacatecas in
Mexico, was performed under conditions of forced labor that killed workers at catastrophic rates.

The silver extracted from these mines transformed the global economy of the sixteenth
and seventeenth centuries. American silver flooded European markets, driving price
inflation across the continent. It flowed to China — then the largest economy in the
world — in exchange for silk and porcelain, creating a genuinely global monetary circuit.
The conquest of the Aztec Empire was therefore not simply a local historical event but a
lever that moved the entire world economy.

## Legacy and Historiography

The interpretation of the conquest has shifted dramatically over time. The conquistadors'
own accounts presented the conquest as a providential victory of Christianity and civilization.
Later nationalist Mexican historiography cast it as the destruction of a sophisticated
indigenous civilization by European violence. Contemporary scholarship tries to hold
both realities simultaneously: the Aztec Empire was real in its achievements and brutal
in its tribute system; the Spanish conquest was militarily and politically sophisticated
and catastrophically destructive in its demographic and cultural consequences. The
descendants of both the conquerors and the conquered inhabit modern Mexico together,
and the meaning of 1521 remains a living political question in ways that few other
events from the same era still do.

The Fall of Tenochtitlán: Cortés, Smallpox, and the End of the Aztec World

// COMMENTS

ON THIS PAGE