(born 1842?, near present-day Rapid City, S.D., U.S.died Sept. 5, 1877, Fort Robinson, Neb.) Oglala Sioux Indian chief. Refusing to abide by an 1868 treaty granting the Sioux a large reservation in the Black Hills, Crazy Horse led his warriors in continued raids against enemy tribes as well as against whites. In 1876 he joined with Cheyenne forces in a surprise attack against Gen. George Crook in southern Montana, forcing Crook's withdrawal. Crazy Horse then united with Chief Sitting Bull for the Battle of the Little Bighorn, where he helped annihilate Lt. Col. George Armstrong Custer's troops. In 1877, his tribe weakened by cold and hunger, Crazy Horse surrendered to Crook; removed to a military outpost in Nebraska, he was killed in a scuffle with soldiers.