sentences:  Mosby's area of operations was Northern Virginia from the Shenandoah Valley to the west, along the Potomac River to Alexandria to the east, bounded on the south by the Rappahannock River, with most of his operations centered in or near Fauquier and Loudoun counties, in an area known as "Mosby's Confederacy".Mosby's command operated mainly within the distance a horse could travel in a day's hard riding, approximately in any direction from Middleburg, Virginia.They also performed raids in Maryland.