Irvin McDowell
Forces in the Shenandoah Valley played an indirect role in the campaign. Approximately 50,000 men under Maj. Gens. Nathaniel P. Banks and Irvin McDowell were engaged chasing a much smaller force under Stonewall Jackson in the Valley Campaign. Jackson's expert maneuvering and tactical success in small battles kept the Union men from reinforcing McClellan, much to his dismay. He had planned to have 30,000 under McDowell to join him.