Jackson's plan was to have Ewell's division move into position at Swift Run Gap to threaten Banks's flank, while Jackson's force marched toward the Allegheny Mountains to assist the detached 2,800 men under Brig. Gen. Edward Allegheny Johnson, who were resisting the advance toward Staunton of Brig. Gen. Robert H. Milroy, the leading element of Maj. Gen. John C. Frémont's army. If Frémont and Banks were allowed to combine, Jackson's forces could be overwhelmed, so Jackson planned to defeat them in detail. Without waiting for Lee's reply, Jackson executed his plan and on April 30, Ewell's division replaced Jackson's men at Swift Run Gap. Jackson marched south to the town of Port Republic in heavy rains and on May 2, turned his men east in the direction of Charlottesville and began marching over the Blue Ridge. To the surprise of his men and officers, whom Jackson habitually left in the dark as to his intentions, on May 4 they boarded trains that were heading west, not east toward Richmond, as they had anticipated. The movement to the east had been a clever deception. On May 5, Jackson's army camped around Staunton, about 6 miles from Johnson's command. On May 7, Milroy received intelligence that Jackson and Johnson were combining against him and he began to fall back toward the Alleghenies.