The Battle of the Little Bighorn, known to the Lakota and other Plains Indians as the Battle of the Greasy Grass, and commonly referred to as Custer's Last Stand, was an armed engagement between combined forces of the Lakota Sioux, Northern Cheyenne, and Arapaho tribes and the 7th Cavalry Regiment of the United States Army. It took place on June 25–26, 1876, along the Little Bighorn River in the Crow Indian Reservation in southeastern Montana Territory. The battle, which resulted in the defeat of U.S. forces, was the most significant action of the Great Sioux War of 1876.
Most battles in the Great Sioux War, including the Battle of the Little Bighorn, were on lands those natives had taken from other tribes since 1851. The Lakotas were there without consent from the local Crow tribe, which had a treaty claim on the area. Already in 1873, Crow chief Blackfoot had called for U.S. military actions against the native intruders. The steady Lakota incursions into treaty areas belonging to the smaller tribes were a direct result of their displacement by the United States in and around Fort Laramie, as well as in reaction to white encroachment into the Black Hills, which the Lakota consider sacred. This pre-existing Indian conflict provided a useful wedge for colonization and ensured the United States a firm Indian alliance with the Arikaras and the Crows during the Lakota Wars.