21st Cavalry Regiment was organized in August, 1862, with companies which had served in the Virginia State Line. The unit was assigned to W.E. Jones' and McCausland's Brigade, and in April, 1864, it contained 317 effectives. It took an active part in various conflicts in East Tennessee, western Virginia, and in the Shenandoah Valley. During mid-April, 1865, the regiment disbanded. Its field officers were Colonel W.E. Peters, Lieutenant Colonel David Edmundson, and Major Stephen P. Halsey.