Lee's army was already on the field and in line of battle as to absolutely require corresponding action. This was Porter's impression at the time, and he conveyed it to McDowell by words and gesture that left no doubt in the mind of the latter that he (Porter) believed the enemy was in force in his immediate front.
In contrast to this evident preparation of the enemy for battle only Porter's 9,000 or 10,000 men were ready for action of the 35,000 men then composing the left wing of the Union army.
Banks' corps, 10,000, was still at Bristoe without orders to move beyond that point. Ricketts' division, 8,000, was near Bristoe, under orders to move to the front, but his men were so worn-out by constant marching, night and day, that they could not possibly be got to the field even for defensive action that day. King's division, 7,000, was just in rear of Porter, but was so fatigued as to be unfit for offensive action, and hardly able to march.
Thus this long column, stretching back from Dawkins' Branch by way of Manassas Junction to and even beyond Bristoe, had struck the right wing of the Confederate army in line of battle, while a gap of nearly 2 miles remained in the Union line between Porter and Reynolds, who was on the left of Sigel, near Groveton.
The accompanying map, marked board map Numbers 1, illustrates the positions of the Union troops at noon of August 29, and the probable positions of the Confederate troops at the same time, as indicated by the information then in possession of the Union generals. This map is not intended to show the actual positions of the troops at that time, but to correctly interpret the information upon which the Union generals then acted.
This was the military situation on the Union left and Confederate right of the field when McDowell arrested Porter's advance, and Porter's operations under the direct orders from Pope heretofore mentioned ceased, and, under new orders just received, Porter became subordinate to McDowell.
Not only had the effort to destroy Jackson before he could be re-enforced totally failed, but the Confederate army was on the field and in line, while the Union army was not. The time to resume defensive action, awaiting the concentration of the army, had not only arrived, but had been too long postponed.
On his way to the front McDowell had received the following order from General Pope, addressed jointly to him and Porter, and Porter had received a copy of the same order a moment before McDowell's arrival:
HEADQUARTERS ARMY OF VIRGINIA,
Centreville, August 29, 1862.
Generals McDOWELL and PORTER:
You will please move forward with your joint commands toward Gainesville. I sent General Porter written orders to that effect an hour and a half ago. Heintzelman, Sigel, and Reno are moving on the Warrenton turnpike, and must now be not far from Gainesville. I desire that as soon as communication is established between this force and your own the whole command shall halt. It may be necessary to fall back behind Bull Run, at Centreville, to-night. I presume it will be son on account of our supplies. I have sent no orders of any description to Ricketts, and none to interfere in any way with the movements of McDowell's troops, except what I sent by his aide-de-camp last night, which were to hold his position on the Warrenton pike until the troops from here should fall upon the enemy's flank and rear. I do not even know Ricketts' position, as I have not been able to find out where General McDowell was until a late hour this morning. General McDowell will take immediate steps to communicate with General Ricketts, and instruct him to rejoin the other divisions of his corps as soon as practicable. If any considerable advantages are to be gained by departing from this order it will not be strictly carried out. One thing must be had