In OTL, at First Bull Run, Stonewall Jackson proved the crucial Southern commander in Confederate victory as he kept his Virginia Brigade together and immobile enough to prevent Union forces from advancing until rebel reinforcements arrived later in the day, turning the tide of the battle. In the process, General Bernard Bee of South Carolina reportedly said “There is Jackson, standing there like a stone wall,” before being shot. In this ATL, however, the stray bullet that killed Bee in OTL instead reaches Jackson, striking him down at the pivotal moment of the battle. Without his leadership, the Virginians waver and do not attempt the OTL capture of Union guns which began the turn of the battle; instead, pounded and pounded by a Union assault and with their charismatic leader dead, the brigade falters and eventually begins to dissipate at 1430 hours.
The Union Army under Irwin McDowell thus slowly sweeps the Confederate Army off of the field, despite General Beauregard’s best attempts to reform his lines, and arrives at Manassas Junction in enough time to surprise the newly-arrived forces of Joe Johnston. Unable to bring himself to attack in the face of Beauregard’s rout and McDowell’s advance, Johnston (as he often would in OTL) orders a general withdrawal towards Richmond; however, only Jubal Early’s cavalry are able to slow down the Union onslaught and keep the Confederate army from being utterly annihilated; the rest of the army quickly breaks into chaos. Worst of all, however, is the fact that, as in OTL, Jefferson Davis has arrived on the field to monitor the progress of battle. Here, however, he is overwhelmed by the rout and thus cannot escape before being taken prisoner by the Union advance guard. The Union advances as far as Warrenton Junction before, tired and at the limit of their supply train, they finally regroup. By the end of the day, the Confederate forces are finally consolidated about 10 miles north of Rappahannock Station; exhausted, severely demoralized by Jackson’s death and Davis’ capture, and having acquired roughly 3,500 casualties, the Rebel army seems to be in no position to resist the Union advance.