On 31 May-13 August 1521, the Siege of Tenochtitlan was fought between the Spanish under Hernan Cortes against the Aztecs under Cuauhtémoc during the Spanish Conquest of Mexico.
Why did it happen?
The Aztec Empire had been founded in 1428 as a Triple Alliance of three city-states (Tenochtitlan, Texcoco and Tacuba) in the valley of Mexico. In 1519, 27 years after Christopher Columbus discovered the West Indies, Hernan Cortes sailed from Cuba with 600 infantry, 17 cavalry and 10 artillery to the Yucatan Peninsula on an expedition approved by the Spanish Crown. After forming an alliance with the Tlaxcala, Cortes advanced on the Aztec capital, Tenochtitlan, and took the Aztec emperor, Montezuma II, hostage. In 1520, a Spanish military expedition was sent to arrest Cortes for insubordination, but the leader of the group was in turn apprehended by Cortes and his soldiers incorporated into Cortes’ own army. Upon returning to Tenochtitlan, Cortes and his men faced an Aztec revolt and were driven out of the city on 30 June in what became known as the “Night of Sorrows.” On 7 July, Cortes and his men defeated an Aztec army at the Battle of Otumba before withdrawing to Tlaxcala to begin preparations for the conquest of Tenochtitlan. By April 1521, most of the Aztecs’ tributaries had joined the Tlaxcala as allies of the Spanish while the Aztecs were led by a new emperor named Cuauhtémoc who began to prepare for the defence of the city.
Who was involved?
The Spanish army at Tenochtitlan numbered 810 infantry, 90 cavalry, 18 artillery, 13 brigantines, and 75,000 Tlaxcala warriors. Brigantines were small warships propelled by sail and oar with cannon mounted on their bow, each carrying a crew of 25 men. While Cortes commanded the brigantines on Lake Texcoco, The Spanish soldiers and Tlaxcala warriors were divided into three sections at the end of a causeway, which consisted of 150 Spanish infantry, 30 Spanish cavalry and 25,000 Tlaxcala warriors each: Pedro de Alvarado commanded the northwest causeway near Tacuba; Cristobel de Olid commanded the southwest causeway near Coyoacan, and Gonzalo de Sandoval commanded the northeast causeway near Tepeyacac. Cortes also left one causeway free in case the Aztecs were forced to fight to the death, although few took this route during the siege. The Spanish plan was to cut off the city’s supply of water and advance down each causeway, supported by the brigantines on the lake, and gradually take control of them while applying military pressure on the Aztecs. The Aztec army at Tenochtitlan numbered 250,000 warriors and civilians. The Aztec army consisted of warriors wearing the skins of eagles and jaguars who wielded swords, clubs, and spears made of wood and obsidian stone. The Aztec plan at Tenochtitlan was to defend the city at all costs and play upon the Spanish horror of human sacrifice by capturing Spanish soldiers and sacrificing them to the god Huitzilopochtli to demoralize the Spaniards.
What happened?
On 31 May, after destroying the aqueduct that supplied fresh water to Tenochtitlan, the Spanish brigantines under Hernan Cortes took command of Lake Texcoco by carving a swathe through the hundreds of Aztec canoes with their cannons and crewmen armed with arquebuses and crossbows. Beginning on 10 June, the three columns of Spanish and Tlaxcala warriors under Alvarado, Olid and Sandoval began to mount a series of advances down the causeways leading to the city. After coming under attack by Aztec warriors, the Spanish-Tlaxcala forces withdrew and attacked the causeways afresh over the next three weeks. During one attack on 30 June, 69 Spanish soldiers were captured and ritually sacrificed by the Aztecs. Cortes then suspended the assault on the city and sent troops to intimidate nearby settlements to stop them from joining the Aztecs. By 15 July, hunger and disease had begun to decimate the Aztec forces, and the Spanish resumed their assault on Tenochtitlan. After heavy fighting, Cortes moved his headquarters to a tent on one of the city’s rooftops. On 12 August, the Spanish captured the Aztec emperor, Cuauhtémoc, while he was trying to flee in a canoe across the lake, and the following day the Spanish mounted one last assault that overwhelmed the remaining Aztecs and captured the city for Spain. During the 11-week siege, the Spanish and Tlaxcala lost 20,000 warriors while the Aztecs sustained 100,000 killed and 40,000 captured.
What changed as a result?
The Siege of Tenochtitlan was a decisive Spanish victory. In many ways, it decided the fate of the Americas for the next 500 years. In the wake of the Spanish victory at Tenochtitlan came the enslavement, forced religious conversion, cultural collapse, and decimation of the Native Americans by diseases such as smallpox. In 1524, the Mayans of the Yucatan Peninsula were conquered by Pedro de Alvarado at the Battle of Acajutla, while the following year the last emperor of the Aztecs, Cuauhtémoc, was hanged by Cortes for treachery against his Spanish captors. The siege also had far-ranging consequences for Europe with an estimated 100 tons of gold and 6,785 tons of silver, the equivalent of $6.3 million according to one estimate, being exported back to Europe to fund the wars of Charles V (r.1519-1556) and Philip II (r.1556-1598) of Spain. Although this vast wealth caused such a rise in prices that it nearly wrecked the financial system of Europe, Spain became the dominant political, military, and economic power in Europe until its defeat by France at the Battle of Rocroi in 1643.
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