Hernán Cortés gained experience in Spanish Caribbean colonization before undertaking the mainland expedition of 1519. Governor Diego Velázquez attempted to withdraw his authorization, but Cortés proceeded and established a municipal base at Veracruz to support a claim of direct loyalty to the crown. His force depended on Indigenous guides, interpreters, and allies. Malintzin, also known as Malinche, played a crucial role in communication and negotiation with societies whose interests did not coincide with those of the Mexica state.

Cortés advanced to Tenochtitlan in 1519 and took Moctezuma II captive. Spanish efforts to control the city combined coercion, alliance building, and attempts to manage opposition from other Spaniards sent against him. Violence during his absence helped trigger open conflict, and his force was driven from the city in 1520. Returning with Indigenous allies, particularly Tlaxcalans, he mounted a siege using land forces and vessels on the lake. Tenochtitlan fell in August 1521 after devastating fighting and the effects of epidemic disease.

The conquest cannot be understood as the accomplishment of a small Spanish party alone. Indigenous rivalries and military participation were decisive, while smallpox and other disruptions undermined the defenders. Cortés became governor and captain general of New Spain, overseeing reconstruction and the establishment of colonial authority. The new order involved demands for labor and tribute, conversion, and redistribution of land and power. His reports to the king defended his conduct and sought recognition, making them important but self-interested sources.

A difficult expedition to Honduras in 1524–1526 included the execution of Cuauhtémoc, the captured Mexica ruler. Complaints and royal inquiries restricted Cortés's political authority. In 1529 he received the title Marquis of the Valley of Oaxaca but did not recover unrestricted government of the colony. He pursued Pacific expeditions and further claims before returning to Spain, where he died in 1547. His career helped establish Spanish rule over central Mexico and produced wealth and status, but also destruction and dispossession on a vast scale. Later heroic and condemnatory images alike can simplify a history involving many Indigenous actors. The durable consequences of his work lie in colonial institutions and unequal relations created through war, negotiation, and coercion, rather than in the misleading image of a solitary conqueror.