(1874 - 1877).
As in the East, expansion into the plains and mountains by miners, ranchers and settlers led to increasing conflicts with the indigenous population of the West. Many tribes — from the Utes of the Great Basin to the Nez Perces of Idaho — fought the whites at one time or another. But the Sioux of the Northern Plains and the Apache of the Southwest provided the most significant opposition to encroachment on tribal lands. Led by resolute, militant leaders, such as Red Cloud and Crazy Horse, the Sioux were skilled at high-speed mounted warfare. The Sioux were new arrivals on the Plains—previously they had been sedentary farmers in the Great Lakes region. Once they learned to capture and ride horses, they moved west, destroyed other Indian tribes in their way, and became feared warriors. Historically the Apache bands supplemented their economy by raiding others and practiced warfare to avenge a death of a kinsman. The Apache bands were equally adept at fighting and highly elusive in the environments of desert and canyons.
In 1875, the last serious Sioux war erupted, when the Dakota gold rush penetrated the Black Hills. The U.S. Army did not keep miners off Sioux (Lakota) hunting grounds; yet, when ordered to take action against bands of Sioux hunting on the range, according to their treaty rights, the Army moved vigorously. In 1876, after several indecisive encounters, General George Custer found the main encampment of the Lakota and their allies at the Battle of Little Big Horn. Custer and his men — who were separated from their main body of troops — were all killed by the far more numerous Indians who had the tactical advantage. They were led in the field by Crazy Horse and inspired by Sitting Bull's earlier vision of victory.