Crow Dog was a Brulé subchief who lived on the Great Sioux Reservation, in the part that is now the Rosebud Indian Reservation in south-central South Dakota on its border with Nebraska. The tribe had made several treaties with the United States, the most significant being the 1868 Treaty of Fort Laramie. This treaty provided that Indians agreed to turn over those accused of crimes to the Indian agent, a representative of the U.S. government in Indian affairs. The treaty also stipulated that tribal members would stay on the reservation provided (which included the Black Hills) unless three-fourths of the adult male tribal members agreed otherwise. In 1874, Colonel George Armstrong Custer led a party into the Black Hills to investigate rumors of gold. Once he announced the discovery of gold on French Creek, the Black Hills Gold Rush brought prospectors into that area in violation of the Fort Laramie treaty. The Lakota protested in 1875 to no avail, as the United States demanded that the Lakota sell the Black Hills. The United States then declared the Lakota as hostile, which started the Black Hills War. The war included the Battle of the Rosebud, the Battle of the Little Bighorn and the Battle of Slim Buttes, among others. The war ended in 1877. Crow Dog fought in this war, while the man he later killed, Spotted Tail, did not. Congress passed a law later in 1877 () that took the Black Hills away from the tribe, contrary to the language of the treaty.