Relatively speaking, the conquest of the once mighty Aztec Empire in Mexico by the Spanish did not take very long. It began in early 1519 and ended in late 1521. It was not easy, however, mostly because the Spanish did not present a unified front to the Aztecs. The Spanish fought each other almost as much as they did with the Aztecs. This infighting jeopardized the expedition and almost led to its ruin.
Spanish involvement in Mexico began in February of 1519 when the Spanish governor of Cuba, Diego Velasquez, authorized Hernan Cortez to led a reconnaissance force into Mexico to investigate rumors of a wealthy civilization in central Mexico. Although Velasquez changed his mind about Cortez and later ordered him to remain in Cuba, Cortez ignored these orders and departed with a small army of 400 soldiers and 100 sailors. He landed at Vera Cruz, gained control of the city, and sent a letter to the King of Spain, the Holy Roman Emperor Charles V, in which Cortez solicited the support of the king.
At this point, Cortez burned his ships to prevent the possibility of a mutiny. Without ships, the soldiers had to conquer Mexico if they ever wanted to return home. Soon afterwards, Cortez and his army discovered the Tlaxcalan people. After two weeks of fighting, the Tlaxcalans surrendered and joined Cortez in his campaign against the Aztecs. After defeating the Aztecs at Choula, the Spanish and their Tlaxcalan allies came to Tenochtitlan, the Aztec capital.
They were initially greeted by the Aztec Emperor, Moctezuma II, who thought that Cortez was the Aztec god Quetzacoatl. Quetzacoatl was prophesied to arrive the same year Cortez did, and Moctezuma II thought Cortez's pale skin, armor, and advanced technology were signs of his deity. Hoping to appease Cortez, Moctezuma gave the Spaniards lavish gifts of gold and jewels. Nevertheless, Cortez and his men captured the Aztec Emperor and held him for ransom. They had believed that this would prevent any attempt at revolt among the Aztecs. Those beliefs proved unfounded, however, because the Aztecs came to view Moctezuma as a traitor. When the Spanish brought him out to talk to the people, they threw stones at him. He died of those injuries a few days later.
Before the death of Moctezuma, however, Cortez had to deal with a Spanish army sent by Velasquez to arrest Cortez for his disobedience. He left 200 men in Tenochtitlan and went to meet the other Spanish army. Cortez and his men entered the other army's camp at night and captured their leader. Most of the rest of the men were more than willing to join Cortez because of the immense wealth he promised them. When Cortez returned to the Aztec capital, however, he found the city in revolt. When an attempt to get Moctezuma to appease the people failed, Cortez was forced to flee from the city.
The Spanish left Tenochtitlan on the night of June 30, 1520. By the time they arrived at Tlaxcala, they had lost half of their men. Soon, however, the Spanish were able to regroup and they conquered the Aztec cities one by one until they finally regained control of Tenochtitlan on August 13, 1521. 40,000 Aztecs died during the siege of Tenochtitlan alone and many more died of disease and famine all over the country afterwards. The fall of Tenochtitlan marks the collapse of the Aztec Empire and the beginning of Spanish control in Mexico.
