Following the Great Sioux War of 1876-77 and the defeat of U.S. Army forces led by General George Armstrong Custer at the Battle of Little Big Horn on June 25, 1876, and the defeat and capture of the Nez Perce, band of Chief Joseph by the U.S. Army in the Battle of Bear Paw in 1877, General Phil Sheridan suggested that a fort be built on or near the Milk River to ward off possible attacks from the North by the Sioux led by Chief Sitting Bull, who had migrated to the Cypress Hills in Canada, or by the Nez Perce, some of whom were also in Canada. Lt. Col. J.R. Brooke recommended the site where the post was established. The fort is located in Hill County six miles southwest of Havre (the county seat) on Highway 87. It was named for the Siouan-speaking Assinniboine people. The Native Americans never attacked from Canada.