The Spaniard Cabeza de Vaca was the leader of the Narváez expedition of 600 men that between 1527 and 1535 explored the mainland of North America. From Tampa Bay, Florida, on 15 April 1528, they marched through Florida. Traveling mostly on foot, they crossed Texas, New Mexico and Arizona, and Mexican states of Tamaulipas, Nuevo León and Coahuila. After several months of fighting native inhabitants through wilderness and swamp, the party reached Apalachee Bay with 242 men. They believed they were near other Spaniards in Mexico, but there was in fact 1500 miles of coast between them. They followed the coast westward, until they reached the mouth of the Mississippi River near to Galveston Island.