As Union Maj. Gen. George B. McClellan prepared to march his Army of the Potomac up the Virginia Peninsula and capture Richmond, Confederate Gen. Joseph E. Johnston ordered Maj. Gen. Thomas J. "Stonewall" Jackson to prevent Union troops in the Shenandoah Valley from reinforcing McClellan. After his tactical defeat at the First Battle of Kernstown, Jackson moved up the valley to confront a Union force entering it from western Virginia. Joining forces with Brig. Gen. Edward "Allegheny" Johnson's Army of the Northwest, Jackson moved to McDowell to intercept the Union force gathering there, the brigades of Brig. Generals Robert H. Milroy and Robert C. Schenck. Jackson's infantry, supported by artillery, took a position on Sitlington's Hill, a mile-long rocky spur overlooking the Union camp beside the Bull Pasture River. Late in the afternoon, Milroy and Schenck attacked Jackson, using the cover of ravines and woods. The Federals were repulsed after severe fighting, lasting four hours. After the battle, Milroy and Schenck withdrew to the west, freeing up Jackson’s army to march against the other Union columns threatening the Valley. Jackson's victory at McDowell set the stage for his hard-marching, hard-fighting 1862 campaign that, over the next month, kept Union troops penned up in the Valley.