However, they did not win their battle.  The Southern army under Beauregard lay near the Bull Run river, some twenty miles from Washington, covering the railway junction of Manassas on the line to Richmond.  The main Northern army, under General McDowell, a capable officer, lay south of the Potomac, where fortifications to guard Washington had already been erected on Virginian soil.  In the Shenandoah Valley was another Southern force, under Joseph Johnston, watched by the Northern general Patterson at Harper’s Ferry, which had been recovered by Scott’s operations.  Each of these Northern generals was in superior force to his opponent.  McDowell was to attack the Confederate position at Manassas, while Patterson, whose numbers were nearly double Johnston’s, was to keep him so seriously occupied that he could not join Beauregard.  With whatever excuse of misunderstanding or the like, Patterson made hardly an attempt to carry out his part of Scott’s orders, and Johnston, with the bulk of his force, succeeded in joining Beauregard the day before McDowell’s attack, and without his gaining knowledge of this movement.  The battle of Bull Run or Manassas (or rather the earlier and more famous of two battles so named) was an engagement of untrained troops in which up to a certain point the high individual quality of those troops supplied the place of discipline.  McDowell handled with good judgment a very unhandy instrument.  It was only since his advance had been contemplated that his army had been organised in brigades.  The enemy, occupying high wooded banks on the south side of the Bull Run, a stream about as broad as the Thames at Oxford but fordable, was successfully pushed back to a high ridge beyond; but the stubborn attacks over difficult ground upon this further position failed from lack of co-ordination, and, when it already seemed doubtful whether the tired soldiers of the North could renew them with any hope, they were themselves attacked on their right flank.  It seems that from that moment their success upon that day was really hopeless, but some declare that the Northern soldiers with one accord became possessed of a belief that this flank attack by a comparatively small body was that of the whole force of Johnston, freshly arrived upon the scene.  In any case they spontaneously retired in disorder; they were not effectively pursued, but McDowell was unable to rally them at Centreville, a mile or so behind the Bull Run.  Among the camp followers the panic became extreme, and they pressed into Washington in wild alarm, accompanied by citizens and Congressmen who had come out to see a victory, and who left one or two of their number behind as prisoners of war.  The result was a surprise to the Southern army.  Johnston, who now took over the command, declared that it was as much disorganised by victory as the Northern army by defeat.  With the full approval of his superiors in Richmond, he devoted himself to entrenching his position at Manassas.  But in Washington, where rumours of victory had been arriving all through the day of battle, there prevailed for some time an impression that the city was exposed to immediate capture, and this impression was shared by McClellan, to whom universal opinion now turned as the appointed saviour, and who was forthwith summoned to Washington to take command of the army of the Potomac.