Political map of North America & the Caribbean 25 June 1876 (Great Sioux War): In 1874, gold was discovered in the Black Hills (Custer's 1874 Black Hills Expedition), part of the Great Sioux Reservation. When attempts by the US government to purchase the land collapsed in 1876, it decided to send in the cavalry to subjugate the more hostile Lakota Sioux and Northern Cheyenne living west of the Reservation (Great Sioux War). Despite a notable victory at Little Bighorn (Battle of the Little Bighorn), the Indians were ultimately forced to surrender.