Fort Randall was the U.S. Army's principal military and supply post on the Upper Missouri from 1856 to 1892. Its soldiers protected settlers crossing the plains, monitored the Sioux and other regional tribes, and supplied a chain of forts extending westward to the northern Rockies. They took part in numerous campaigns against the tribes and also tried to keep miners out of sacred tribal lands encompassing the Black Hills. Chief Sitting Bull, of Little Bighorn fame, was imprisoned at the fort for two years. By the time the Army abandoned Fort Randall, the region was permanently settled, and the chapel's ruins remained the fort's sole aboveground survivor.