[124] south of Fredericksburg; and McClellan, to clear all opposition from his path, sent forward Porter's corps to Hanover Junction, where he had a sharp encounter with a force of the enemy under General Branch, whom he repulsed with a loss of two hundred killed and seven hundred prisoners, and established the right of the Army of the Potomac within fifteen miles, or one march, of McDowell's van. McDowell was eager to advance, and McClellan was equally anxious for his arrival, when there happened an event which frustrated this plan and all the hopes that had been based thereon. This event was the irruption of Stonewall Jackson in the Shenandoah Valley. The keen-eyed soldier at the head of the main Confederate army, discerning the intended junction between McDowell and McClellan, quickly seized his opportunity, and intrusted the execution of a bold coup to that vigorous lieutenant who had already made the Valley ring with his exploits.
Jackson, on retiring from his last raid in the Shenandoah Valley, which had ended in his repulse by Shields at Winchester (March 27), had retreated up the Valley by way of Harrisonburg, and turning to the Blue Ridge, took up a position between the south fork of the Shenandoah and Swift Run Gap. Here he was retained by Johnston, after the main body of the Confederate army had been drawn in towards Richmond. Jackson was joined by Ewell's division from Gordonsville on the 30th April, and at the same time he received the further accession of the two brigades of General Edward Johnson, who had held an independent command in Southwest Virginia. This raised his force to about fifteen thousand men. Banks' force, reduced by the detachment of Shields' division, sent to General McDowell, to about five thousand men, was posted at Harrisonburg. Fremont was at Franklin, across the mountains; but one of his brigades, under Milroy, had burst beyond the limits of the Mountain Department, and seemed to be moving to make a junction with Banks, with the design, as Jackson thought, of advancing on Staunton. Jackson determined to attack these forces in
