The Columbian Exchange
Hernán Cortés (1485-1547) was perhaps the most famous of the Spanish conquistadors, the conqueror of the mighty Aztec Empire of Central America. From 1519 to 1521, Cortés commanded the small Spanish expedition that eventually captured the Aztec capital of Tenochtitlan, allowing Cortés to take over as governor of Mexico. His willful disregard for authority pitted him against his superiors in Cuba and in Spain, and although his exploits were legendary and quite profitable, he died an embittered man in 1547.
Without the advantageous impacts of the Columbian Exchange, Cortés's conquest of the Aztecs would have been impossible. In 1520, smallpox—a European disease for which the Aztecs had no immunities—ravaged the population of Tenochtitlan, infecting as much as half the population. The smallpox pandemic fatally weakened the Aztecs, allowing Cortés to prevail one year later.