On June 2d, Brig.-Gen. G. T. Beauregard took command of the Confederate troops on the "Alexandria line." His main line of defense was behind Bull run, and his headquarters at Manassas Junction, 26 miles from Alexandria and the Potomac river. This army then held the line of the Potomac from the Blue ridge down to the vicinity of Washington, thence around the already partially fortified Virginia front of that city to the Potomac, and then south along that river to Chesapeake bay.
The only advantages of the line of Bull run to the Confederates were strategic. It was, by public roads, about 20 miles from the Potomac, a distance over which the movements of the Federal army could be easily watched; and it covered the junction of the Orange & Alexandria railroad—which had connection at Gordonsville, by the Virginia Central, with Richmond, the capital of the Confederacy, and with Staunton, a great depot of supplies and the most important town in the Shenandoah valley—with the Manassas Gap railroad, which led from Manassas Junction to Strasburg in the lower valley of the Shenandoah, giving quick connection with the army there operating under Gen. J. E. Johnston.
Excellent highways from Alexandria and Washington, and from other important points to the northwest and southwest, converged at Centreville, about 3 miles east of Bull run, offering great advantages for the concentration of the Federal army in the immediate front of this line; while roads diverging from the same village to the northwest, west and southwest, made it an easy matter to maneuver troops for offensive operations upon the flanks of a defensive army holding the line of Bull run. There were also excellent positions on the north-eastern side of that stream for holding the defensive army in check in front of its center while flanking movements to either hand were in process of execution.
The Federal army of invasion consisted of five divisions: The First, under Brig.-Gen. Daniel Tyler, was composed of four brigades of infantry and four batteries of regular United States artillery; the Second, under Col. D. M. Hunter, of two brigades of infantry, a battalion of United States cavalry, a battery of regular United States artillery, and two volunteer batteries; the Third, under Col. S. P. Heintzelman, of three brigades of infan-
