Under these orders General Porter advanced promptly with his corps, followed by King's division, on the direct road from Manassas Junction toward Gainesville, having knowledge of the military situation as above described.
General Porter had met General McDowell near Manassas Junction, and they had conversed with each other relative to this order, placing King's division under Porter's command. McDowell claims that it was conceded that he might go forward and command the whole force under the Sixty-second Article of War, but he desired to reunite all the divisions of his corps on that part of the field where Reynolds then was. Hence he wrote to Pope on this subject, awaited his orders, and did not exercise any command over Porter's corps until after the receipt of further orders from Pope.
When, about 11.30 o'clock, the head of Porter's column arrived at Dawkins' Branch, about 3 1/2 miles from Gainesville and 9 1/2 miles from Thoroughfare Gap, he met the enemy's cavalry advance, and captured some of Longstreet's scouts. The clouds of dust in his front and to his right, and extending back toward Thoroughfare Gap, showed the enemy coming in force, and already arriving on the field in his front.
Morell's division was at once deployed; Sykes closed up in support, King's division following. A regiment was sent forward across the creek as skirmishers, and Butterfield's brigade was started across the creek to the front, and somewhat to the right, with orders to seize, in advance of the enemy, if possible, the commanding ground on the opposite ridge, about a mile distant. Morell's division, with Sykes' in support, was ready to advance at once to the support of Butterfield.
At this stage of Porter's operations, some time between 11.30 and 12 o'clock, McDowell, in person, arrived on the field and arrested the movement Porter was making, saying to him, in the hearing of several officers, "Porter, you are too far out. This is no place to fight a battle," or words to that effect.
McDowell had received a few minutes before a dispatch from Buford, informing him that seventeen regiments of infantry, a battery, and some cavalry had passed through Gainesville at 8.45 o'clock, and moved down the Centreville road toward Groveton, and hence must have been on the field in front of Sigel and Reynolds at least two hours.
The dust in Porter's immediate front and extending across toward Groveton, as well as back toward Gainesville, showed that large forces of the enemy, in addition to those reported by Buford, were already on the field. The latest information from the Confederate army showed the whole force of the enemy within reach of Gainesville by noon on the 29th. McDowell's troops (Ricketts' division and some cavalry) had delayed Longstreet's advance at Thoroughfare Gap from about noon until dark on the previous day, 28th. Hence Lee's column had had eighteen hours by the morning of the 29th of close up in mass near the Gap, and seven hours that morning in which to march 8 miles and form line on the field of battle.
Jackson, who had been supposed anxious to retreat, and for whom the way had been left open, had not retreated, but was still holding his position of the previous evening, as if confident of adequate re-enforcements. Sigel's pursuit had been checked, where it started that morning, at Groveton.
It was certain that the head of column of Lee's main army had arrived on the field in front of Groveton at least two hours in advance of the arrival of the head of column of Porter's and McDowell's corps at Dawkins' Branch, and it was so nearly certain that the main body of