"Near present-day St. Augustine, Spanish explorer Juan Ponce de Leon comes ashore on the Florida coast, and claims the territory for the Spanish crown.
Although other European navigators may have sighted the Florida peninsula before, Ponce de Leon is credited with the first recorded landing and the first detailed exploration of the Florida coast. The Spanish explorer was searching for the "Fountain of Youth," a fabled water source that was said to bring eternal youth. Ponce de Leon named the peninsula he believed to be an island "La Florida" because his discovery came during the time of the Easter feast, or Pascua Florida.
In 1521, he returned to Florida in an effort to establish a Spanish colony on the island. However, hostile Native Americans attacked his expedition soon after landing, and the party retreated to Cuba, where Ponce de Leon died from a mortal wound suffered during the battle. Successful Spanish colonization of the peninsula finally began at St. Augustine in 1565, and in 1819 the territory passed into U.S. control under the terms of the Florida Purchase Treaty between Spain and the United States."
This Day in History - History Channel