that post was abandoned, Loudoun served as point of crossing between the Piedmont and the Shenandoah Valley, as well as between Virginia and Maryland. All of the Army of Northern Virginia passed through the county on its way to Antietam, while the Army of the Potomac crossed the county on its way back from that battle. Again in 1863 the Army of the Potomac used Loudoun to get to and return from Gettysburg. Finally, in 1864, Jubal Early and his Federal pursuers used Loudoun to pass from the D.C. environs to the Shenandoah Valley after the Battle of Fort Stevens. In all, the county changed hands six during the course of the war, and the passing of the armies led to many small conflicts in the county. The Confederate occupation June 1861 - March 1862 Rockville Expedition Skirmish at Conrad's Ferry, June 17, 1861 Skirmish at Edward's Ferry, June 18, 1861; July 29, 1861 McClellan's operations in Northern Virginia Battle of Ball's Bluff and Edwards Ferry, October 20–23, 1861 Battle of Dranesville, December 21, 1861 Border skirmishes Skirmish at River Mill, September 15, 1861 The Federal invasion by Colonel John Geary March 1862 - August 1862 In early 1862, the Union army began amassing at Harper's Ferry in preparation for operations in the Shenandoah Valley. Part of this force, under the command of Col. John W. Geary, was charged with the undertaking of securing Loudoun County and the army's left flank from across the Blue Ridge as it operated in the Valley. On February 24, Geary set out across the Potomac from Harpers Ferry, but high water delayed his crossing, and it was not until the 27th that his force was fully across into Loudoun. Geary placed his artillery atop an eminence of Short Hill Mountain and proceeded with his main force to occupy Lovettsville, a German settlement in the heart of Unionist Loudoun, where he established his headquarters. On March 6, Brigadier General D.H. Hill was ordered to abandon Loudoun County to join with Gen. Joseph E. Johnston in Richmond to halt McClellan's drive up the Virginia Peninsula. The following day, Geary's force left its camp at Lovettsville. As Hill retreated, his forces set fire to Confederate supplies, nearby forage and the Carolina Road's bridge over Goose Creek. By the end of the day, Union forces occupied Leesburg, establishing headquarters at Fort Johnston, rechristened Fort Geary, and imposing martial