Loudoun County in the Civil War —Loudoun County, Virginia, was destined to be an area of significant military activity during the American Civil War. Located on Virginia's northern frontier, the Potomac River, Loudoun County became a borderland after Virginia's secession from the Union in early 1861. Loudoun County's numerous Potomac bridges, ferries and fords made it an ideal location for the Union and Confederate armies to cross into and out of Virginia. Likewise, the county's several gaps in the Blue Ridge Mountains that connected the Piedmont to the Shenandoah Valley and Winchester were of considerable strategic importance. The opposing armies would traverse the county several times throughout the war leading to several small battles, most notably the Battle of Balls Bluff.