After the retreat from Kernstown, Jackson's force remained in the southern Shenandoah Valley awaiting orders and preparing for battle. In April, Jackson received orders to keep the Union forces in the Valley occupied with the goal of preventing them from joining McClellan's army near Richmond. Also coming to Jackson's camp were reinforcements commanded by Major General Richard Ewell. Meanwhile, another Union force was moving against Jackson's army. Major General John C. Frémont's Mountain Department was moving towards Jackson from the west, across the Allegheny Mountains. Frémont's advance force consisted of 3,500 men commanded by Brigadier General Robert Milroy. Milroy reached the town of McDowell in early May, and was reinforced by another 2,500 men under Brigadier General Robert C. Schenck on 8 May.