Loudoun County in early 1864 belonged to a partisan ranger battalion that operated outside the rules other armies followed. John Singleton Mosby commanded the 43rd Battalion Virginia Cavalry, and he ran the territory between the Blue Ridge and the Potomac as his own dominion - Mosby's Confederacy, the locals called it. His Rangers slept in farmhouses scattered across the region, riding when the bugle called and disappearing into civilian life between raids. The Federals could rarely catch them. Major Charles Russell Lowell, commanding the Union cavalry brigade headquartered near Vienna, had been ordered to break Mosby's grip. By February he had tried raids, ambushes, and counter-raids. None of it worked. So on February 21, the day after Cole's Maryland Cavalry returned bruised from Upperville, Lowell dispatched another column - 167 troopers of the 2nd Massachusetts and 16th New York Cavalry, led by Captain James Sewall Reed of San Francisco. Reed had volunteered for the assignment.

On the morning of February 22, one hundred sixty Rangers gathered near Middleburg to bury Bill McCobb, a partisan thrown from a horse two days earlier when it tried to jump a fence. Funerals in Mosby's Confederacy were brief affairs - the war did not pause for grief. While the Rangers stood graveside, a scout brought word that Reed's column had ridden into Leesburg and turned east on the turnpike. Mosby moved immediately. He sent the bulk of the battalion under William Henry Chapman south toward Ball's Mill while he and a small party shadowed Reed. When the Federals camped six miles east of Leesburg for the night, Mosby rejoined Chapman near Guilford Station - the railroad stop the locals would later rename Sterling. By dawn the next morning, the Rangers were in position west of Dranesville. Mosby split them into three wings: a dismounted blocking squad on the pike itself, with mounted companies concealed in the woods on either side. A handful of riders rode west as bait.

At eleven o'clock the Federal vanguard appeared, chasing the skirmish party. The flanking companies sprang from the trees - too early. The main Federal column was still behind, untouched. Reed saw the mistake and seized it, ordering an immediate counterattack. The two forces collided in the road in a swirl of horses, pistols, and sabers. Ranger John Munson captured a Federal trooper but forgot to take the man's sidearm. When Munson turned to rejoin the fight, the prisoner shot him in the back. Moments later, Baron Robert von Massow - a young Prussian soldier of fortune riding with the Rangers - captured Reed himself and made the same mistake. Reed shot von Massow in the back. William Chapman, riding up at that moment, killed Reed in retaliation. The Federal resistance broke instantly. With their captain dead and the Rangers closing from every direction, troopers spurred north toward the Potomac in flight. Some plunged their horses into the cold river. Several drowned.

When the Rangers tallied the day, the numbers were stark: twelve Federals killed, twenty-five wounded, seventy captured, and a hundred horses taken. The Rangers lost five wounded and one killed. By any measure of the American Civil War, this was a complete tactical victory for a partisan force less than a year old. Reed's body was carried back to Federal lines under flag of truce. Von Massow survived his wound and eventually returned to Europe, where he later became a Prussian general. Munson recovered as well. The skirmish is sometimes called the Ambush at Anker's Shop after a roadside store near the action, but the Rangers themselves called it 2nd Dranesville - a battle on the same turnpike where Confederate Brigadier General J.E.B. Stuart had been bloodied two years earlier, in a very different kind of fight. For Mosby, it was one more proof that the small, mobile, locally-connected force could humiliate the better-equipped army that hunted it. He would keep humiliating them until Appomattox.