Siege of Tenochtitlán II

Siege of Tenochtitlán II

The siege and capture of the Aztec capital of Tenochtitlán was the most important event in the Spanish conquest of Mexico. The Aztecs, or people from Aztlan in the north (they were also known as the Mexica), came to dominate much of the region. Their society was highly developed, with a complex governmental structure and long-distance trade, but they had limited scientific knowledge and no modern weaponry.

In the mid-14th century the Aztecs established their capital in the city of Tenochtitlán (present-day Mexico City) on an island on the western side of Lake Texcoco connected to the shore by long causeways. The Aztecs worshiped Huitzilopochtli (the god of the sun and war) and other deities. Believing that daily human sacrifices were necessary to keep the sun healthy and shining, they built altars to Huitzilopochtli and the other gods in the form of great pyramids that dominated the city. On special days thousands of prisoners might be sacrificed. This practice did not endear the Aztecs to their conquered peoples and created ready allies for the Spanish. Ultimately Tenochtitlán came to be a large and wealthy city of approximately 60,000 buildings and 200,000 people, perhaps one-fifth of the total Aztec population. A million or so Aztecs ruled a subject population of perhaps 5 million.

In 1519, 34-year-old Hernán Cortés landed on the west coast of Mexico from his base in Cuba under orders to establish a coastal trading post. Cortés, however, was determined to explore the mysterious land of the west, which was rumored to abound in gold. Cortés commanded a small force of 550 men with some 17 horses and 10 small cannon. In August he began his march to the interior, and during the next month he defeated the Tlaxcalan people in a series of battles and captured their capital of Tlaxcala. The Tlaxcalans then allied themselves with the Spanish.

In November 1519 Emperor Montezuma II received Cortés at Tenochtitlán with all possible honors. The Spanish, who were dazzled by the gold and wealth of the capital, soon made clear their intention to rule. Cortés was able to capitalize in part on the Aztec belief in a great white god, Quetzalcoatl, whose return had been prophesied. With their horses, metal armor, and firearms, the Spanish could play the part.

Following the death of some Spanish soldiers on the coast near Veracruz, Cortés seized Montezuma and began to rule through him. This worked until Cortés sought to introduce Christianity. In the spring of 1520 Cortés departed Tenochtitlán to do battle with a rival Spanish force sent by his superior, Cuban governor Diego Velázquez, to punish Cortés for disobeying orders. Cortés defeated that force and added the men he captured to his own forces.

On his return to Tenochtitlán, Cortés discovered that his lieutenant Pedro de Alvarado, whom he had left in charge, was under siege by the Aztecs. While Cortés was able to reestablish his authority, the situation in the city soon deteriorated, and warfare resumed. Montezuma was killed, but his brother Cuitlahuac had already been elected emperor by chiefs determined to fight the Spanish. Aztec numbers now prevailed over Spanish firepower, and on the night of June 30–July 1 (La Noche Triste as it was known to the Spanish, or “The Sad Night”) Cortés and many of his followers were forced to fight their way out of the city. They lost most of the gold they had hoped to bring out along with 600 men and two-thirds of their 68 horses. The Aztecs harassed the Spanish in their retreat all the way to Tlaxcala.

Rather than pursue a guerrilla war, Emperor Cuitlahuac chose to fight a set-piece battle where the Aztec warriors came up against horse cavalry for the first time. At Otumba on July 7, the Spanish used their 28 horses to great advantage, driving against the conspicuously dressed Aztec leadership to win a victory in which thousands of Aztecs were killed.

Cortés then spent several months rebuilding his force. He sent ships to Jamaica to fetch replacement artillery and horses. At the same time Cortés had his men construct 13 small brigantines to approach Tenochtitlán across Lake Texcoco. Each vessel carried 25 Spanish soldiers and 12 native rowers.

Cortés was also aided by a surprise ally, for unwittingly the Spanish had brought smallpox to the New World. The natives had absolutely no resistance to the disease, which wiped out much of the population. Cuitlahuac was among those who perished. Cuauhtemoc, a son-in-law of Montezuma, succeeded Cuitlahuac as emperor.

In early 1521 Cortés was ready to move. The Spanish and their native allies began their approach to Tenochtitlán by taking control of towns around Lake Texcoco. By April this was complete. The Spanish had 184 harquebusiers, crossbowmen, and men-at-arms along with 86 horsemen, perhaps 700 infantry, and 18 artillery pieces. They were greatly aided by some 50,000 allied Tlaxcalans who opposed Aztec rule. Cortés divided his forces into three main groups under his lieutenants Alvarado, Gonzalo de Sandoval, and Cristóbal de Olid.

On May 26 forces under Sandoval and Alvarado destroyed the great aqueduct at Chapultepec, cutting off the water supply to Tenochtitlán. Five days later the Aztecs mounted an attack with hundreds of canoes across the lake. The Spaniards used cannon fire to destroy most of the canoes and win control of the lake. That same day Cortés launched an attack on Tenochtitlán. Some crossbowmen were able to land in the city, but they were soon driven out.

The fighting continued for 10 weeks, during which the Spaniards were able to view the sacrifice by the Aztecs atop the great pyramid of those the Aztecs had taken prisoner. At night the defenders made fresh breaks in the causeways providing access to the city, but the Spaniards and their allies were able to repair them. The Aztecs mounted human wave attacks, which the Tlaxcalans defeated at high cost. Finally, on August 13 Cortés launched an assault that brought victory the next day. Only a few Aztec survivors escaped in canoes. Reportedly, 150,000 people died in the city. One Spanish eyewitness said that it was impossible to walk in Tenochtitlán without stepping on corpses.

Following the capture of Tenochtitlán, Cortés set about completely dismantling Aztec society and replacing it with Spanish civilization. He was assisted in this by the continued ravages of smallpox that may have wiped out 90 percent of the native population. Within a generation both the Aztec language and religion had disappeared. Spain would be the dominant power in the region for the next 300 years.


Carrasco, David. Montezuma’s Mexico. Niwot: University of Colorado Press, 1992.

Diaz del Castillo, Bernal. The Discovery and Conquest of Mexico, 1517–1521. Translated by A. P. Maudslay. New York: Harper, 1928.

White, Jon Manchip. Cortés and the Downfall of the Aztec Empire. London: Hamish Hamilton, 1971.