During the Great Sioux War that started after Sitting Bull refused to relocate to agency land, warriors led by Crazy Horse killed George Armstrong Custer and his men at the Battle of the Little Big Horn. The slaughter took place during the Centennial, and the Indian victory was announced to the nation on July 4, while angry Americans demanded retribution. Grant castigated Custer in the press, saying "I regard Custer's massacre as a sacrifice of troops, brought on by Custer himself, that was wholly unnecessary—wholly unnecessary." Previously, Custer had infuriated Grant when he testified against Grant's brother Orville during a House investigation into trading post graft on March 1, 1876. In September and October 1876, Grant convinced the tribes to relinquish the Black Hills. Congress ratified the agreement three days before Grant left office in 1877.