After the Civil War, as the volunteer armies disbanded, the regular army cavalry regiments increased in number from six to ten, among them Custer's U.S. 7th Cavalry Regiment of Little Bighorn fame, and the African-American U.S. 9th Cavalry Regiment and U.S. 10th Cavalry Regiment. The black units, along with others (both cavalry and infantry), collectively became known as the Buffalo Soldiers. According to Robert M. Utley: