On the afternoon of March 20 Col. Reno, commanding a 1000-man expedition, consisting of the Loudoun Rangers, 12th Pennsylvania Cavalry, 1st United States Infantry and 2 pieces of light artillery, set out from Harpers Ferry into Loudoun County on a mission to obtain forage and clear the Loudoun Valley of partisans. The column entered Loudoun in the Between the Hills valley and marched through Hillsboro and Woodgrove, reaching Purcellville on the morning of the 21st. The column was under near continuous sniping fire from Confederate partisans during the march, 5 of which were captured at Hillsboro.
