HEADQUARTERS ARMY OF VIRGINIA,
Near Ball's Cross-Roads, September 3, 1862.

DEAR GENERAL: My whole command retired in good order, and now are encamped between the outer and inner line of entrenchments, except the three corps sent by way of Vienna and Lewinsville to Chain Bridge, from whom I have not yet heard.

I sent a regiment of cavalry this morning to Vienna and beyond to ascertain the movements of the enemy. The rear guards of the forces retiring by the Alexandria pike and by Vienna were fired on with artillery, but not to any considerable extent. The whole command is much broken down, especially that portion of it originally constituting the Army of Virginia, which has done the most harassing service, and has been, without the intermission of a day, fighting the enemy since the 9th of August.

A few days' rest will restore them, and they will then be capable of rendering good service, although greatly reduced in numbers.

Banks' corps does not exceed 6,000, McDowell's 11,000, and Sigel's 6,000. There are, of course, many stragglers, who will swell these numbers considerably within a few days.

Of those portions of the Army of the Potomac which have joined me (excepting Sumner's and Franklin's, of which I know little) not much can be expected. They are listless and dejected, and straggle in a manner which is distressing. Not more, certainly, that one-half of those reported effective can ever be brought into action, and even those that can be do not manifest the least spirit.

Reno's command is a very fine one, but does not exceed 6,000. Sumner and Franklin arrived too late to be of service, as the army had been cut up wearied to death before they reached Centreville.

I have much to say and to report to your concerning the conduct of certain officers and their commands during these operations, which I will postpone for the present. There is no doubt in the mind of any man here that the battle of Groveton would have been a decisive and complete victory on the first day had General Potter advanced as I directed him. Why he did not is yet unexplained. The whole of the heavy re-enforcements which attacked us on Saturday passed down the road from Gainesville during the whole afternoon and night of Friday, while General Porter remained in full sight of them, on their flank, between Manassas Junction and Gainesville, although he had my positive written order to attack them in flank while I was urging the battle in front. He made no attack whatever, but retired a portion of his command, at least, to Manassas, which was not near enough the next day to take any part in the action.

This is the second time since it has been with me that the delay of this same corps has hazarded the safety and success of our movements. The constant complaint is that the men are broken down, though what marching or other hard service they have done for a long time I do not know.

I will state these facts officially within a day or two, or as soon as I can find a moment to make my report.

I have done the best I possibly could with the materials furnished me, as I am very sure you know. Some definite arrangements, it seems to me, ought to be made about command here. Troops assigned to different commanders are much mixed up by the efforts to place each division and brigade on the ground formerly occupied by them. It would be greatly more satisfactory to everybody if you would command the whole direct from Washington, assigning certain portions of the