Overview
In 1519 Hernán Cortés landed on the Gulf coast of Mexico with about 500 men. By August 1521 the Mexica (Aztec) capital, Tenochtitlan Key term · c. 1325–1521 Tenochtitlan The Mexica capital, built on an island in Lake Texcoco, with causeways, canals and a great temple precinct. Why it matters One of the largest cities in the world in 1519. Its fall in August 1521 marked the collapse of Mexica power, and Mexico City was built on its ruins as the capital of New Spain. See in glossary → , lay in ruins and its last ruler, Cuauhtémoc, was a prisoner. The conquest was not simply a Spanish achievement: it depended on Indigenous allies who saw the Spaniards as a means to overthrow Mexica domination — and on an epidemic that devastated the city.
Key dates
- 1519 Cortés lands, founds Veracruz, and allies with the Totonacs and then the Tlaxcalans Key term · 1519–1521 Tlaxcalans The people of Tlaxcala, an independent Nahua state that had resisted Mexica conquest. Why it matters Their alliance with Cortés supplied the bulk of the fighting force against Tenochtitlan. They show that the "Spanish" conquest was also an Indigenous war — and they were rewarded with privileges under colonial rule. See in glossary → .
- Oct 1519 Spaniards and Tlaxcalans massacre nobles and townspeople at Cholula.
- 8 Nov 1519 Cortés enters Tenochtitlan and is received by Moctezuma II, whom he soon takes hostage.
- May 1520 Pedro de Alvarado’s men massacre Mexica nobles at the festival of Toxcatl.
- 30 Jun 1520 The Noche Triste Key term · 30 June – 1 July 1520 Noche Triste Spanish for "the sad night" — the Spaniards' disastrous night-time escape from Tenochtitlan, in which many were killed on the causeways. Why it matters The Mexica had defeated the invaders. Cortés's survival depended on retreating to Tlaxcala, whose loyalty — and the smallpox epidemic that followed — allowed him to return. See in glossary → : the Spaniards flee the city with heavy losses. Moctezuma has died.
- Late 1520 Smallpox sweeps through the Valley of Mexico, killing the new ruler, Cuitláhuac.
- May–Aug 1521 The siege of Tenochtitlan; the city falls on 13 August 1521.
- 1542 The New Laws Key term · 1542 New Laws Laws issued by Charles I (Emperor Charles V) banning the enslavement of Indigenous people and ordering the phasing out of encomiendas. Why it matters They showed the Crown's concern — driven by reformers such as Las Casas and by the wish to control the colonists — but settler resistance forced key provisions to be withdrawn in 1545. See in glossary → attempt to limit the encomienda Key term · 16th century Encomienda A grant by the Spanish Crown to a colonist of the labour and tribute of a group of Indigenous people, in return for protecting them and instructing them in Christianity. Why it matters In practice it enabled severe exploitation and contributed to population decline, prompting the reforms of the New Laws. See in glossary → .
- 1550–1551 The Valladolid debate Key term · 1550–1551 Valladolid debate A formal debate in Spain between Bartolomé de las Casas, who defended the full humanity and rights of Indigenous peoples, and Juan Ginés de Sepúlveda, who argued that conquest was justified. Why it matters It was one of the first European debates about the rights of colonised peoples. It produced no clear verdict, but shaped later arguments about empire and human rights. See in glossary → on the rights of Indigenous peoples.
The Mexica Empire in 1519
The Mexica ruled a tributary empire from their island capital in Lake Texcoco. Tenochtitlan had perhaps 200,000 inhabitants, larger than any city in Spain. Conquered peoples paid heavy tribute and supplied victims for human sacrifice, and powerful enemies — above all Tlaxcala — remained unconquered. Those resentments were the conquistadors’ greatest asset.
We were amazed and said that it was like the enchantments they tell of in the legend of Amadis, on account of the great towers and cues and buildings rising from the water, and all built of masonry.
Why this quote matters
Díaz wrote decades later, partly to defend ordinary soldiers' claims against official accounts that glorified Cortés. His wonder at the city is valuable evidence of Tenochtitlan's scale — and of how the conquerors framed the New World through European romances. (“Cues” is the conquistadors' word for temple-pyramids.)
Why did the conquest succeed?
Indigenous allies. Tlaxcala and other altepetl (city-states) provided tens of thousands of warriors, porters and supplies. For them this was a war against the Mexica, in which the Spaniards were useful allies. The final siege was fought largely by Indigenous armies.
Disease. Smallpox, to which the population had no immunity, killed a large part of Tenochtitlan’s population in 1520, including Cuitláhuac, just as the Mexica had driven the Spaniards out.
Translation and intelligence. Malintzin Key term · 1519–1520s Malintzin (La Malinche) A Nahua woman, also called Doña Marina, who became Cortés's interpreter, adviser and mistress. Why it matters Her knowledge of Nahuatl, Maya and Mesoamerican politics made negotiation and alliance-building possible. In Mexican memory she has been seen both as a traitor and as a survivor with little choice. See in glossary → , a Nahua woman given to the Spaniards, interpreted and advised Cortés, allowing him to negotiate and exploit political divisions.
Technology and tactics. Steel weapons, armour, horses, crossbows and a few cannon gave the Spaniards advantages in close combat; brigantines built for the siege controlled the lake. Their importance is easy to overstate: guns were few and gunpowder scarce.
Different ways of war. Mesoamerican warfare often aimed to capture enemies for sacrifice rather than kill them; the Spaniards fought to destroy.
Impact
- Population collapse. Repeated epidemics and exploitation reduced the Indigenous population of central Mexico dramatically over the sixteenth century.
- Colonial rule. Tenochtitlan was rebuilt as Mexico City, capital of New Spain. Spaniards were granted Indigenous labour and tribute through the encomienda, while Indigenous nobles often kept local authority under Spanish rule.
- Religion. Franciscan and other missionaries led mass conversions, destroying temples and codices, but also recording Nahua culture — as in Bernardino de Sahagún’s Florentine Codex.
- Debate in Spain. Friars such as Bartolomé de las Casas condemned the conquistadors’ cruelty, leading to the New Laws of 1542 and the Valladolid debate of 1550–51.
The Nahua perspective survives in accounts recorded after the conquest. One lament begins:
Broken spears lie in the roads; we have torn our hair in our grief.
Why this quote matters
Written within a decade of the fall, this is one of the few Indigenous voices on the conquest. It records defeat as catastrophe rather than as the liberation some of the Spaniards' allies may have hoped for.
Historians’ debate
Prescott told the conquest as the heroic achievement of Cortés and a small band of Spaniards — a view that shaped popular understanding for more than a century.
Hassig argued that the conquest must be understood through Mesoamerican politics: the Spaniards succeeded because they became part of an Indigenous war against Mexica dominance.
Restall challenged myths such as the “handful of adventurers”, the idea that the conquest was complete in 1521, and the belief that Indigenous people saw the Spaniards as gods.
Test yourself
Why were the Tlaxcalans willing to fight alongside the Spaniards? Reveal
Tlaxcala was an independent enemy of the Mexica, surrounded by Mexica territory and at constant war with them. After initially fighting the Spaniards, its leaders saw an alliance as the best way to defeat their old enemy.
How did smallpox affect the course of the conquest? Reveal
It struck Tenochtitlan in 1520, soon after the Spaniards had been driven out, killing much of the population and the ruler Cuitláhuac. It weakened the city’s defence before the siege of 1521.
What did the New Laws of 1542 try to do, and why did they fail? Reveal
They tried to protect Indigenous people by banning their enslavement and phasing out the encomienda. Settlers in the Americas resisted fiercely — in Peru they rebelled — and the Crown withdrew the most controversial provisions.
Key terms
- Encomienda 16th century
-
A grant by the Spanish Crown to a colonist of the labour and tribute of a group of Indigenous people, in return for protecting them and instructing them in Christianity.
Significance: In practice it enabled severe exploitation and contributed to population decline, prompting the reforms of the New Laws.
- Malintzin (La Malinche) 1519–1520s
-
A Nahua woman, also called Doña Marina, who became Cortés's interpreter, adviser and mistress.
Significance: Her knowledge of Nahuatl, Maya and Mesoamerican politics made negotiation and alliance-building possible. In Mexican memory she has been seen both as a traitor and as a survivor with little choice.
- New Laws 1542
-
Laws issued by Charles I (Emperor Charles V) banning the enslavement of Indigenous people and ordering the phasing out of encomiendas.
Significance: They showed the Crown's concern — driven by reformers such as Las Casas and by the wish to control the colonists — but settler resistance forced key provisions to be withdrawn in 1545.
- Noche Triste 30 June – 1 July 1520
-
Spanish for "the sad night" — the Spaniards' disastrous night-time escape from Tenochtitlan, in which many were killed on the causeways.
Significance: The Mexica had defeated the invaders. Cortés's survival depended on retreating to Tlaxcala, whose loyalty — and the smallpox epidemic that followed — allowed him to return.
- Tenochtitlan c. 1325–1521
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The Mexica capital, built on an island in Lake Texcoco, with causeways, canals and a great temple precinct.
Significance: One of the largest cities in the world in 1519. Its fall in August 1521 marked the collapse of Mexica power, and Mexico City was built on its ruins as the capital of New Spain.
- Tlaxcalans 1519–1521
-
The people of Tlaxcala, an independent Nahua state that had resisted Mexica conquest.
Significance: Their alliance with Cortés supplied the bulk of the fighting force against Tenochtitlan. They show that the "Spanish" conquest was also an Indigenous war — and they were rewarded with privileges under colonial rule.
- Valladolid debate 1550–1551
-
A formal debate in Spain between Bartolomé de las Casas, who defended the full humanity and rights of Indigenous peoples, and Juan Ginés de Sepúlveda, who argued that conquest was justified.
Significance: It was one of the first European debates about the rights of colonised peoples. It produced no clear verdict, but shaped later arguments about empire and human rights.