The First Battle of Kernstown was fought on March 23, 1862, in Frederick County and Winchester, Virginia, the opening battle of Confederate Maj. Gen. Thomas J. "Stonewall" Jackson's campaign through the Shenandoah Valley during the American Civil War. Attempting to tie down the Union forces in the Valley, under the overall command of Maj. Gen. Nathaniel P. Banks, Jackson received incorrect intelligence that a small detachment under Col. Nathan Kimball was vulnerable, but it was in fact a full infantry division more than twice the size of Jackson's force. His initial cavalry attack was forced back and he immediately reinforced it with a small infantry brigade. With his other two brigades, Jackson sought to envelop the Union right by way of Sandy Ridge. But Col. Erastus B. Tyler's brigade countered this movement, and, when Kimball's brigade moved to his assistance, the Confederates were driven from the field. There was no effective Union pursuit. Although the battle was a Confederate tactical defeat, it represented a strategic victory for the South by preventing the Union from transferring forces from the Shenandoah Valley to reinforce the Peninsula Campaign against the Confederate capital, Richmond. Following the earlier Battle of Hoke's Run, the First Battle of Kernstown may be considered the second among Jackson's rare defeats. Background Jackson's division had been withdrawing "up" the Valley (to the higher elevations at the southwest end of the Valley) to cover the flank of Gen. Joseph E. Johnston's army, withdrawing from the Centreville–Manassas area to protect Richmond. Without this protective movement, the Federal army under Banks might strike at Johnston through passes in the Blue Ridge Mountains. By March 12, 1862, Banks occupied Winchester just after Jackson had withdrawn from the town, marching at a leisurely pace 42 miles up the Valley Pike to Mount Jackson. On March 21, Jackson received word that Banks was splitting his force, with two divisions (under Brig. Gens. John Sedgwick and Alpheus S. Williams) returning to the immediate vicinity of Washington, D.C., freeing up other Union troops to participate in Maj. Gen. George B. McClellan's Peninsula Campaign against Richmond. The remaining division, under Brig. Gen. James Shields, was stationed at Strasburg to guard the lower (northeastern) Valley, and intelligence indicated that it was withdrawing toward Winchester. Banks made preparations to leave the Valley personally on March 23. Jackson's orders from Johnston were to prevent Banks's force from leaving the Valley, which it