 American involvement in the Everglades began during the Second Seminole War ( 1836 – 42 ) , a costly and very unpopular conflict . The United States spent between $ 30 million and $ 40 million and lost between 1 @,@ 500 and 3 @,@ 000 lives . The U.S. military drove the Seminoles into the Everglades and were charged with the task of finding them , defeating them , and moving them to Oklahoma Indian territory . Almost 4 @,@ 000 Seminoles were killed in the war or were removed . The U.S. military was completely unprepared for the conditions they found in the Everglades . They tore their clothes on sawgrass , ruined their boots on the uneven limestone floor , and were plagued by mosquitoes . Soldiers ' legs , feet , and arms were cut open on the sawgrass and <unk> infection set in , taking many lives and limbs . Many died of <unk> @-@ borne illness . After <unk> through mud , one private died in his tracks of exhaustion in 1842 . General Thomas <unk> admitted the military was overwhelmed by the terrain when he wrote to the Secretary of War in 1838 , trying to dissuade him from prolonging the war . 
