The Rangers have the distinction of being the only unit raised in present-day Virginia to serve in the Union Army.

Secretary of War Edwin M. Stanton issued Means orders to raise a company of men to serve as an independent command, of which he would be captain, for special service in Loudoun and along the Virginia-Maryland border.

Recruiting operations were established in the northern Loudoun Valley, an area of strong unionist sentiment, eventually leading to the formation of 2 companies.

For the first two years of service the Loudoun Rangers served as partisans, often in conjunction with Cole's Maryland Cavalry (1st Potomac Home Brigade) fighting their confederate counterparts, such as White's Comanches, Mosby's Rangers and John Mobberly's renegade band in and around Loudoun.

As the war in the valley came to an end, the Rangers returned to their partisan role and were eventually effectively broken up in April 1865 when a detachment of Mosby's Rangers raided their camp at Castleman's Ferry and captured the better part of the command.