In the Americas the Spanish found a number of empires that were as large and populous as those in Europe. However, small bodies of conquistadors, with large armies of indigenous Americans groups, managed to conquer these states. During this time, pandemics of European disease such as smallpox devastated the indigenous populations. Once Spanish sovereignty was established, the Spanish focused on the extraction and export of gold and silver.
In 1512, to reward Juan Ponce de León for exploring Puerto Rico in 1508, king Ferdinand urged him to seek these new lands. He would become governor of discovered lands, but was to finance himself all exploration. With three ships and about 200 men, Léon set out from Puerto Rico on March 1513. In April they sighted land and named it La Florida—because it was Easter (Florida) season—believing it was an island, becoming credited as the first European to land in the continent. The arrival location has been disputed between St. Augustine, Ponce de León Inlet and Melbourne Beach. They headed south for further exploration and on April 8 encountered a current so strong that it pushed them backwards: this was the first encounter with the Gulf Stream that would soon become the primary route for eastbound ships leaving the Spanish Indies bound for Europe. They explored down the coast reaching Biscayne Bay, Dry Tortugas and then sailing southwest in an attempt to circle Cuba to return, reaching Grand Bahama on July.
In 1517 Cuba's governor Diego Velázquez de Cuéllar commissioned a fleet under the command of Hernández de Córdoba to explore the Yucatán peninsula. They reached the coast where Mayans invited them to land, but were attacked at night and only a remnant of the crew returned. Velázquez then commissioned another expedition led by his nephew Juan de Grijalva, who sailed south along the coast to Tabasco, part of the Aztec empire. In 1518 Velázquez gave the mayor of the capital of Cuba, Hernán Cortés, the command of an expedition to secure the interior of Mexico but, due to an old gripe between them, revoked the charter.
In February 1519 Cortés went ahead anyway, in an act of open mutiny. With about 11 ships, 500 men, 13 horses and a small number of cannons he landed in Yucatán, in Mayan territory, claiming the land for the Spanish crown. From Trinidad he proceeded to Tabasco and won a battle against the natives. Among the vanquished was La Malinche, his future mistress, who knew both (Aztec) Nahuatl language and Maya, becoming a valuable interpreter and counselor. Through her, Cortés learned about the wealthy Aztec Empire.
In July his men took over Veracruz and he placed himself under direct orders of new king Charles V of Spain. There Cortés asked for a meeting with Aztec Emperor Moctezuma II, who repeatedly refused. They headed to Tenochtitlan and on the way made alliances with several tribes. In October, accompanied by about 3,000 Tlaxcaltec they marched to Cholula, the second largest city in central Mexico. Either to instill fear upon the Aztecs waiting for him or (as he later claimed) wishing to make an example when he feared native treachery, they massacred thousands of unarmed members of the nobility gathered at the central plaza and partially burned the city.
Map of the island city Tenochtitlán and Mexico gulf made by one of Cortés' men, 1524
Arriving in Tenochtitlan with a large army, on November 8 they were peacefully received by Moctezuma II, who deliberately let Cortés enter the heart of the Aztec Empire, hoping to know them better to crush them later. The emperor gave them lavish gifts in gold which enticed them to plunder vast amounts. In his letters to Charles V, Cortés claimed to have learned then that he was considered by the Aztecs to be either an emissary of the feathered serpent god Quetzalcoatl or Quetzalcoatl himself—a belief contested by a few modern historians. But he soon learned that his men on the coast had been attacked, and decided to hostage Moctezuma in his palace, demanding a ransom as tribute to Charles V.
Meanwhile, Velasquez sent another expedition, led by Pánfilo de Narváez, to oppose Cortès, arriving in Mexico in April 1520 with 1,100 men. Cortés left 200 men in Tenochtitlan and took the rest to confront Narvaez, whom he overcame, convincing his men to join him. In Tenochtitlán one of Cortés's lieutenants committed a massacre in the Main Temple, triggering local rebellion. Cortés speedily returned, attempting the support of Moctezuma but the Aztec emperor was killed, possibly stoned by his subjects. The Spanish fled for the Tlaxcaltec during the Noche Triste, where they managed a narrow escape while their backguard was massacred. Much of the treasure looted was lost during this panicked escape. After a battle in Otumba they reached Tlaxcala, having lost 870 men. Having prevailed with the assistance of allies and reinforcements from Cuba, Cortés sieged of Tenochtitlán and captured its ruler Cuauhtémoc on August 1521. As the Aztec Empire ended he claimed the city for Spain, renaming it Mexico City.