As Col. Richardson’s brigade battled Gen. Longstreet’s Confederates at Blackburn’s Ford, Gen. Joseph E. Johnston’s Shenandoah Valley command was on the march to Piedmont Station and the Manassas Gap Railroad. Gen. Thomas Jackson’s men arrived first before 8:00 a.m. on July 19. Since no cars or engines were there to carry them, the men broke ranks to rest. When they finally hopped into the cars the Southerners found the rickety ride painfully slow; it took almost eight hours to cover the thirty miles. Everyone was bone tired by the time the train arrived at Manassas Station late that afternoon. Col. Bartow’s men reached Manassas station at 8:00 a.m. on July 20, with Gen. Bee’s jumping from the cars about noon that day. The three Southern brigades marched to the right of the Confederate defensive line behind Bull Run, where they formed a strong reserve. Believing that a major battle was about to be fought, and determined not to miss it, Col. Jeb Stuart rode thirty-six hours with the First Virginia Cavalry to reach the field on the evening of July 20. His exhausted riders fell to the ground behind Bonham’s and Cocke’s brigades.1
By the time the bulk of Johnston’s army arrived, the numbers of the opposing forces equalized considerably, with McDowell fielding 37,000 men to Beauregard’s/Johnston’s 31,000. Johnston’s movement to Manassas, however, frustrated Gen. Beauregard because it was not in keeping with his grand plan. Beauregard wanted Johnston to march against Gen. McDowell’s right flank and savagely attack it, while Beauregard assaulted the Federals in front. Not only did Beauregard’s grand plan fail to materialize, but he officially lost command of the Confederate forces in and around Manassas because Joe Johnston outranked him.2
McDowell had considered moving farther east at Union Mills Ford to turn the Confederate right, but the roads and terrain there made the move impracticable. (Whether the affair at Blackburn’s Ford influenced his thinking is unclear.) McDowell thus shifted his attention to turning the Confederate left flank. The army’s chief engineer, George Barnard, had spent the last two days systematically reviewing the possible Bull Run crossings while McDowell waited for supplies. The best crossing point was over a stone bridge on the macadamized Warrenton Turnpike, but he believed that the sector of the enemy line was heavily defended (it was not) and possibly mined (also untrue). Another good crossing point was a few miles northwest of the bridge at a place called Sudley Ford. According to the latest intelligence, Barnard believed the ford was defended by only a handful of infantry companies and that the crossing would support wheeled vehicles. Confederate patrols may have kept Barnard from even seeing the ford, and two subsequent reconnaissance attempts thrown out for that purpose by McDowell were also turned back.3
McDowell had another vexing problem. The longer he waited to give battle, the smaller his army would become, for the terms of enlistments of his three-month regiments were expiring. He begged the men of the 4th Pennsylvania not to leave just yet, but they remained unconvinced: a deal was a deal, and ninety days was all they bargained for.4
After hearing Barnard’s report about Sudley’s Ford about noon of July 20, McDowell decided he had enough information to formulate a plan to defeat the Confederates. It was an audacious operation. He would leave about one-half of his army to demonstrate in front of Beauregard while the other half marched around the Confederate left flank to fall upon its rear, forcing it to either flee the field completely or fight in the open at a disadvantage. McDowell expected that Gen. Patterson would keep Johnston’s army in the Shenandoah Valley. What McDowell did not know was that the van of Johnston’s army was already close at hand.5
Predicting that McDowell would move to strike the weakly held left side of his line, Beauregard decided that a good offense was the best defense. He convinced Johnston to attack the left side of the Federal line with most of his army. Beauregard made a few modifications, however, including the dispatch of the brigades under Bee and Bartow, together with the Hampton Legion, to the left of his line to reinforce Nathan “Shanks” Evans’ small brigade defending the Stone Bridge.6