During the time of existence of the 43rd Battalion Virginia Cavalry, better known as Mosby's Rangers, Mosby's Command, or Mosby's Raiders, commanded by Colonel John S. Mosby, made many forays in the area known as Mosby's Confederacy which extended from Loudoun County to Fairfax County, Virginia.
The corps took part in the defense of Washington during Jubal Early's Washington Raid of 1864, playing a major role in the defense of Fort Stevens on July 11, 1864.