Maj. Jed. Hotchkiss, Confederate Military History, a library of Confederate States Military History: Volume 3, Virginia
Clement Anselm Evans, Ed.

With this many-roaded problem of offense and defense before him, and his notions of McDowell's designs, Beauregard disposed his forces along Bull run for over a dozen miles in the following order, from right to left, so as to cover all the fords by which he thought McDowell might seek a crossing: At the Union Mills ford, on his extreme right, beyond the railway bridge, he placed Ewell's brigade, supported by that of Holmes, which had arrived from Aquia creek; at McLean's ford, about two miles farther up the stream, D. R. Jones' brigade, supported by Early's; at Blackburn's ford, one mile farther up, Longstreet's brigade; at Mitchell's ford, about a mile farther up stream, Bonham's brigade, which also covered another ford about three-quarters of a mile still farther up and near the mouth of Cub run. Cocke's brigade held the line from Bonham's left, covering Island, Ball's and Lewis' fords, for two miles up the stream to the mouth of Young's branch, three-fourths of a mile below the stone bridge, while Evans' half brigade, under Cocke's command, extended the Confederate line up to and covering the stone bridge, the Warrenton turnpike from Centreville, and a farm ford a quarter of a mile above that bridge. The brigades of the army of the Shenandoah that had already arrived were placed in reserve; those of Bee and Bartow between McLean's and Blackburn's fords, in the rear of Early's and Longstreet's brigades, and Jackson's to the left, between Blackburn's and Mitchell's fords, covering the rear of parts of Longstreet's and Bonham's brigades.

During the night of Saturday, July 20th, the Federal army was thus disposed: Tyler's division was advanced along the Warrenton road and massed about a mile west of Centreville, near Rocky run, and Richardson's brigade of this division was advanced about a mile and a half to the southwest of Centreville, on the road to Blackburn's ford. The remainder of the Federal army, except the reserve divisions left near Centreville and Fairfax, was encamped a short distance to the east of Centreville. After having spent two days reconnoitering along Bull run, McDowell decided to make demonstrations in the Confederate front, on the Warrenton road and on the road to Blackburn's ford, with Tyler's division, while with Hunter's and Heintzelman's he would, by a wide detour of 7 miles or more to the westward and northward.