The Arikara War took place between the United States and the Arikara (a Native American nation also called Arikaree or Ree), in August 1823 near the Missouri River in present-day South Dakota. Arikara warriors had previously attacked a trapping expedition travelling on the river. The United States responded with forces of 230 soldiers, 750 Sioux, and 50 trappers under the command of U.S. Army Colonel Henry Leavenworth.
Although brief, the war (or battle) was noted for two reasons. First, it was the first military conflict between the United States and the western Native Americans, setting the tone for future encounters of the US with the Crow and Blackfeet. Second, Henry Leavenworth did not completely defeat the Arikara. His leniency toward them sparked a great debate between Americans demanding subjugation of the Native Americans and those advocating cohabitation with them.
The Arikara eventually settled with the Mandan and Hidatsa on the Fort Berthold Reservation in North Dakota.