The Shenandoah Valley was a strategic location that both the Federals and the Confederates wanted to control. As a response to George McClellan marching toward Richmond with an army of over 100,000 men, the Confederates came up with a plan. They gave Stonewall Jackson an army of 17,000 men and tasked him with keeping all the troops of Nathaniel P. Banks and John C. Frémont tied up in the Shenandoah Valley. So, Jackson came up with a strategy and executed it successfully, and that's known as the Jackson's Valley campaign.