Hernando de Soto led an expedition to Florida in May 1539. He took 9 ships, 620 men and 220 horses. He landed at a place he called Espiritu Santo, near today's Tampa Bay. His expedition - the first to explore Florida and to document the Mississippi River - was notorious for its brutal violence toward the native peoples it encountered. De Soto died of a fever on May 21, 1542, and was buried along the banks of the Mississippi. Only 300 of his group survived to return to Mexico City.