Beginning in late 1835, Osceola and the Seminole allies began a guerrilla war against the U.S. forces. Numerous generals fought and failed, succumbing to the heat and disease as well as lack of knowledge of the land. It was not until General Thomas Jesup captured many of the key Seminole chiefs, including Osceola who died in captivity of illness, that the battles began to die down. The Seminoles were eventually forced to migrate. Florida joined the Union as the 27th state on March 3, 1845. By this time, almost all of the Seminoles were gone, except for a small group living in the Everglades.