The tribe, having been restricted to the Fort Hall Reservation in Idaho by the Fort Bridger Treaty Council of 1868, were suffering a famine due to white poachers killing cattle and rations which were served just three days a week. A proximate cause of the Bannock War was European settlers' encroachment onto lands that the Bannocks and Shoshones had never ceded by treaty, particularly the Great Camas Prairie. In the spring, Shoshones and Bannocks congregated there to dig the tubers of the camas (Camassia quamash), which they then dried for winter provender, as well as eating them fresh. When they arrived in the spring of 1878, they discovered that the settlers' hogs had rooted up and eaten much of the camas. Because the Bannocks and Shoshones were already on short rations, this increased the animosity and conflict between them and the settlers.
General George Crook, a contemporary United States military officer, commented that
"...it was no surprise...that some of the Indian soon afterward broke out into hostilities, and the great wonder is that so many remained on the reservation. With the Bannocks and Shoshone, our Indian policy has resolved itself into a question of war path or starvation, and being merely human, many of them will always choose the former alternative when death shall at least be glorious."
Led by Chief Buffalo Horn the tribe escaped and soon joined with Northern Paiutes from the Malheur Reservation under Chief Egan and the Umatilla tribes. Chief Buffalo Horn would have known that success was highly unlikely, as he had served as a scout for General Oliver Otis Howard during the Nez Perce War the previous year. The two procured food by raiding settlements of the white settlers. The United States government of the time sent General Oliver Otis Howard to aggressively quell the raids: he achieved victory in two battles. Following a massacre in present-day Charles' Ford, Wyoming, of 140 Native Americans, the tribes surrendered.