Reva, South Dakota Reva, South Dakota Reva is an unincorporated community in Harding County, South Dakota, United States. Although not tracked by the Census Bureau, Reva has been assigned the ZIP code of 57651. The community has the name of Reva Bonniwell, the daughter of a first settler. The Battle of Slim Buttes occurred here on September 9–10, 1876, in the Great Sioux Reservation between the United States Army and Miniconjou Sioux during the Great Sioux War of 1876. It marked the first significant victory for the Army since the stunning defeat of General George Custer at the Battle of Little Bighorn in
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