History of Montana degree of longitude northward to the boundary line of the British possessions. The boundaries of Montana territory did not change during its existence. Montana was admitted to the Union as the state of Montana on November 8, 1889. The Battle of the Little Bighorn—also called Custer's Last Stand and the Battle of the Greasy Grass—was an armed engagement between a Lakota (Sioux)-Northern Cheyenne-Arapaho combined force and the 7th Cavalry of the United States Army. It occurred June 25–June 26, 1876, near the Little Bighorn River in eastern Montana Territory near present-day Hardin, Montana, on land that today is part of
Battle of the Little Bighorn Sitting Bull's ranks for the summer buffalo hunt. The agents did not take into account the many thousands of these "reservation Indians" who had unofficially left the reservation to join their "uncooperative non-reservation cousins led by Sitting Bull". Thus, Custer unknowingly faced thousands of Indians, including the 800 non-reservation "hostiles". All Army plans were based on the incorrect numbers. Although Custer was severely criticized after the battle for not having accepted reinforcements and for dividing his forces, it must be understood that he had accepted the same official government estimates of hostiles in the area which Terry and Gibbon had