Commanding officer: Colonel George D. Imboden (1862-1863; Imboden was then promoted to brigadier general)
Colonel George H. Smith (1863 – 1865)
Field officers: Lt. Colonel David E. Beall, Major Alex. Monroe
Organized in September, 1862 the organization was first known as 1st Regiment Partisan Rangers. The unit was composed of cavalry and infantry until December 1862, when the cavalry companies were united with other companies to form the 18th Cavalry Regiment. Four companies from the 25th Regiment were added in January 1863.
The unit was assigned to Imboden´s and W.L.Jackson´s Brigade. After participating in the Gettysburg Campaign, it skirmished with Federals in western Virginia. Served later in the Shenandoah Valley and was disbanded in April 1865.