Army of the Potomac
General Joseph E. Johnston’s Army of the Potomac continued to be concentrated in Northern Virginia around Manassas, although elements were stationed as far forward as the Potomac River. On October 24 a small action was fought at Ball’s Bluff, on the Potomac River outside Leesburg. It was a Union disaster with relatively small casualties but long-ranging results on the Union war effort.
Confederate authorities were concerned about a possible threat up the Shenandoah Valley towards Winchester, which was guarded only by militia units. On October 22, 1861 it was decided to create the Valley District, which would “embrace the section of country between the Blue Ridge and the Alleghany Mountains.” Major General Thomas J. Jackson was given command and made his headquarters at Winchester.