At Manassas I found Major General Fitz John Porter's corps coming up, and soon after, in answer partly to a message of mine, I received your order of the 29th* from Centreville, addressed jointly to General Porter and myself. In compliance with it, King's and Rickett's division were directed, as soon as they could be placed on the road from Manassas Junction to Gainesville, which runs nearly west, to follow in the rear and close to General Porter's corps. Both these division had been on foot night and day for several days past, had marched the most of the night before, and were separated from their baggage and subsistence. They moved forward, however, cheerfully. The column coming to a halt, I rode forward and found General Porter at the head of his corps, on a slight eminence; in front was an open piece of ground, and beyond it the woods skirting the Warrenton road, down which, as we could see from the dust above the trees, the enemy was moving from Gainesville upon Groveton, where the battle was now going on.
Just before reaching General Porter I received a note from General Buford, commanding cavalry brigade, who was on our then left and front, acquainting me with the strength of the enemy, which he had seen as they passed through Gainesville, the moving down the road. It consisted of seventeen regiments, one battery, and 500 cavalry. As this was an inferior force to General Porter's, I decided for him to throw himself at once on the enemy's flank, and as the head of my column was some 3 miles back, near the Sudley Springs road, I would move it directly north on that road upon the field the battle was then at its height. Under the authority they gave me I deviated from the letter of your instructions, for I thought in this way the forces could be soonest and best applied, and that by coming up on the left of the line, then actually engaged with the enemy, the best disposition would be effected, and the fixed point in your instructions, which was "that the troops should occupy a position from which they could reach Bull Run that night or the next morning," would be still fulfilled.
Leaving General Porter I returned to the head of my two divisions and turned them immediately north, on the Sudley Springs road, to the battle ground, and after seeing most of them off I rode forward to the head of King's division, now commanded by Brigadier-General Hatch, General King, who had the misfortune to be struck down by a severe illness on the Rapphannock, but who had since tried to return to duty, being at last forced to relinquish the command. I found General Hatch absent. He had gone, as I was told, to see General Sigel.
General Reynolds reports that in the mean time, after I had left him in the morning, he had,agreeably to my orders to support General Sigel in any movement the latter might make, formed his division on the left of General Schenck's, but the right of the enemy's position being discovered upon the heights above Groveton, on the right of the Warrenton turnpike, the division advanced in that direction, Cooper's battery, supported by Meade's brigade, coming gallantly into action on the same ridge on which the enemy's right was posted. By some movement in General Sigel's corps Reynolds' right becoming unsupported, and the enemy's whole fire being concentrated upon it, he was obliged to fall back.
Later in the day General Pope, arriving on the right of the line from Centreville, renewed the attack on the enemy, and drove him back some distance. General Reynolds was then directed to threaten the enemy's right and rear, which he proceeded to do under a heavy fire
*See Pop to McDowell and Porter, among inclosure, p.76, to Pope's report.