Sitting Bull in their land, as specified in the 1868 Treaty of Fort Laramie. It was alarmed at reports of Sioux depredations (encouraged by Sitting Bull). In November 1875, President Grant ordered all Sioux bands outside the Great Sioux Reservation to move onto the reservation, knowing full well that not all would comply. As of February 1, 1876, the Interior Department certified as "hostile" those bands who continued to live off the reservation. This certification allowed the military to pursue Sitting Bull and other Lakota bands as "hostiles". Based on tribal oral histories, historian Margot Liberty theorizes many Lakota bands allied with
Sitting Bull River (known as the Greasy Grass River to the Lakota) on June 25, 1876. The U.S. Army did not realize how large the camp was. More than 2,000 Native American warriors had left their reservations to follow Sitting Bull. Inspired by a vision of Sitting Bull's, in which he saw U.S. soldiers being killed as they entered the tribe's camp, the Cheyenne and Lakota fought back. Custer's badly outnumbered troops lost ground quickly and were forced to retreat. The tribes led a counter-attack against the soldiers on a nearby ridge, ultimately annihilating them. The Native Americans' victory celebrations were short-lived.