Overview
The Spanish conquest of the Aztec empire was one of the most significant events in the Spanish colonization of the Americas. The Spanish campaign began in February 1519, and was declared victorious on August 13, 1521, when a coalition army of Spanish forces and native Tlaxcalan warriors led by Hernándo Cortés and Xicotencatl the Younger captured the emperor Cuauhtemoc and Tenochtitlan, the capital of the Aztec empire. The fall of the Aztec empire was the key event in the formation of the Spanish overseas empire, with New Spain, which later became Mexico, a major component.
Hernándo Cortés
Conquest of the Aztecs
During the campaign, Cortés was given support from a number of tributaries and rivals of the Aztecs, including the Totonacs and the Tlaxcaltecas, Texcocans, and other city-states particularly bordering Lake Texcoco. In their advance, the allies were tricked and ambushed several times by the people they encountered. After eight months of battles and negotiations, which overcame the diplomatic resistance of the Aztec emperor Moctezuma II to his visit, Cortés arrived in Tenochtitlan on November 8, 1519, where he was welcomed by Moctezuma and took up residence. When news reached Cortés of the death of several of his men during the Aztec attack on the Totonacs in Veracruz, he took the opportunity to take Moctezuma captive; Moctezuma allowed himself to be captured as a diplomatic gesture. Capturing the indigenous ruler was standard operating procedure for Spaniards in their expansion in the Caribbean, so capturing Moctezuma had considerable precedent.
When Cortés left Tenochtitlan to return to the coast and deal with the expedition of Pánfilo de Narváez, Pedro de Alvarado was left in charge. Alvarado allowed a significant Aztec feast to be celebrated in Tenochtitlan, and in the pattern of the earlier massacre in Cholula closed off the square and massacred the celebrating Aztec noblemen. The biography of Cortés by Francisco López de Gómara contains a description of the massacre. The Alvarado massacre at the Main Temple of Tenochtitlan precipitated rebellion by the population of the city. When the captured emperor Moctezuma II, now seen as a mere puppet of the invading Spaniards, attempted to calm the outraged populace, he was killed by a projectile. Cortés, who by then had returned to Tenochtitlan, and his men fled the capital city during the Noche Triste in June 1520. The Spanish, Tlaxcalans, and reinforcements returned a year later, on August 13, 1521, to a civilization that had been wiped out by famine and smallpox. This made it easier to conquer the remaining Aztecs.
Aftermath
To reward Spaniards who participated in the conquest of what is now contemporary Mexico, the Spanish crown authorized grants of native labor in particular indigenous communities via the encomienda. The indigenous were not slaves, chattel bought and sold or removed from their home community, but the system was one of forced labor. The indigenous of Central Mexico had practices rendering labor and tribute products to their polity's elites, and those elites to the Mexica overlords in Tenochtitlan, so the Spanish system of encomienda was built on pre-existing patterns. The Spanish conquerors in Mexico during the early colonial era lived off the labor of the indigenous. Due to some horrifying instances of abuse against the indigenous peoples, Bishop Bartolomé de las Casas suggested importing black slaves to replace them (he later repented when he saw the even worse treatment given to the black slaves).
Nevertheless, Aztec culture survives today. Modern-day Mexico City is built on the site of the Aztec capital, Tenochtitlan. There are still 1.5 million people who speak the Aztec language of Nahuatl, and part of the Mexica migration story appears on the Mexican flag.