East of Warrenton
Sigel had finally cleared out of Reynolds’ way, and the Pennsylvania Reserves could begin marching up the Warrenton Turnpike [US 29] towards the old battlefield. But Reynolds was barely underway before it became obvious that Sigel had seriously botched his job. Pickets began to report that there were no Union troops to the right of the Reynolds’ men.
Over the course of the several hours it took Reynolds and McDowell to figure out what happened, Sigel marched his entire corps south and formed it up to the right of the O&A tracks, rather than marching with his right-most brigade on the railroad. This left a massive gap between McDowell’s corps and Sigel’s, though how massive would not be immediately apparent. Thinking that Sigel must be only a mile or two separated, McDowell gave orders to the senior brigadier of King’s Division to follow behind Reynolds on the turnpike, but send out flankers to look for Sigel.
For a little over an hour the advanced scouts of Longstreet’s Wing had been cautiously trying to determine what force was felling trees in the gap. With nearly all of the cavalry commanded by Stuart and east of Bull Run Mountain, Longstreet couldn’t reconnoiter like he should have.
Had he been able to, he would have learned that the only Union force opposing him was the First New Jersey Cavalry, once again under the ludicrous Sir Percy Wyndham. Always reckless, Colonel Wyndham had decided that he would hold the Gap, and sent messengers to McDowell to hurry infantry reinforcement while his cavalry cut down trees and hid themselves throughout the narrow gorge.
Despite the delay of McDowell and Sigel, Pope was moving much too quickly for Jackson to strike him at Manassas Junction, so he pulled his men back to the line of an unfinished railroad. Alternating cuts and banks, the railroad line had been dug by the owners of the Manassas Gap Railroad to avoid the exorbitant fees the O&A owners were charging them for running traffic from Alexandria to Manassas Junction. The line was supposed to diverge from Gainesville and travel north through Fairfax Court-House to Jones Point in Alexandria, where a terminus would have directly served a wharf on the Potomac River.
But the Panic of 1857 had effectively killed the project, drying up capital for its construction, which had ended in 1858, even though the rails for the line had already been purchased and were sitting in Alexandria. Traveling over the rolling Piedmont of Virginia, the railroad had been overwhelmed by the price of cuts and embankments needed to maintain a suitable grade for rail traffic, but it was those cuts and embankments that now offered a solution to Stonewall Jackson.
He placed his division, under Taliaferro, behind the unfinished railroad behind the Brawner family farm, and Ewell’s Division between the farm and the Sudley Road. The railroad bed provided natural cover, behind which the extent of his force could be hidden from Union scouts, and the large, downward sloping plain in front of them provided a perfect killing field if the scouts happened to find them anyway.
It would become the defining geography of the battle.
South of Manassas Junction