The Arikara War took place in August 1823 between the United States and the Arikara native Americans near the Missouri River, in present-day South Dakota. Arikara warriors had previously attacked a trapping expedition traveling on the river. The United States responded with forces of 230 soldiers, 750 Sioux, and 50 trappers[citation needed] under the command of U.S. Army Colonel Henry Leavenworth. The Arikara eventually settled with the Mandan and Hidatsa on the Fort Berthold Reservation in North Dakota. Many Arikaras and Crows became Indian scouts during the height of the Sioux Wars.