By 1876, gold had been discovered in the Black Hills (southwestern South Dakota), a region the Sioux Indians considered sacred and the US government had promised to respect. Although it tried, the US Army count not keep white prospectors out of the area; the Sioux's legitimate grievances against the whites increased. Many roving Indian bands refused to go by the government deadline of February 1, 1876, to the reservations set aside for them. A military expedition was sent out against them. One column under General George Crook (1829-90) destroyed the village of Sioux chief Crazy Horse (1849?-77), but shortly afterward it was defeated by the Indians. Crook retired briefly to obtain reinforcements and then moved north again. Meanwhile, another column under General Alfred Howe Terry (1827-90) was advancing westward from Dakota; it included the Seventh Cavalry led by Colonel George Armstrong Custer (1839-76). When a large Indian band was reported on the Rosebud River (southeastern Montana), the cavalry were sent ahead as scouts, but Custer disregarded his orders and pursued the Indians south to the Little Bighorn River. There, not waiting for reinforcements and unaware or heedless of the numerical superiority of the Indians (about 2,500 Sioux and Cheyenne warriors under Chiefs Sitting Bull (1834-90), Gall (1840?-94), and Crazy Horse), Custer decided to attack immediately and vaingloriously. He divided his command into three units, sending two units farther upstream to encircle and attack the Indians and led the third unit of 266 soldiers in a direct charge on the morning of June 25, 1876. The Indians surrounded Custer on a hill and killed him and every one of his men (later called "Custer's Last Stand"). The two other units failed to relieve Custer; they were attacked and forced to retreat but were saved from annihilation by the arrival of Terry and his troops. Terry and Crook continued their campaign against the Indians, especially the Sioux, with vigor. Crazy Horse was defeated and surrendered in 1877; he was presumably killed while trying to escape. Sitting Bull and Gall and other warriors fled to Canda, and most of the other Sioux were either slain or captured and forced to settle on reservations. In 1881, both Sitting Bull and Gall returned, surrendered, and were pardoned.