Shenandoah Valley The Confederacy feared that Union General George McClellan would receive reinforcements from the numerous troops that had stayed behind to protect Washington. Stonewall Jackson therefore launched a campaign in the Shenandoah Valley. He planned to make the Northerners think he was going to attack Washington. In a series of brilliant moves from May 4 through June 9, 1862 Jackson advanced about 350 miles up the Shenandoah Valley and beyond, toward the Potomac River. His 17,000 men received the name "foot cavalry" because they marched so fast. Jackson won four battles against the Union armies. He reached the Potomac but soon had to retreat. However he had forced the Union to withhold the powerful reinforcements that McClellan had counted on.