Eighty-five wagons were got together by the quartermaster last night, loaded with subsistence, and sent forward, under an escort, at 1 a. m. via Annandale.

Every effort has been made to carry out your instructions promptly. The difficulty seem s to consist in the fact that the greater part of the transportation on hand at Alexandria and Washington had been needed for current supplies of the garrisons. At all events such is the state of the case as represented to me by the quartermasters, and it appears to be true. I take it for granted that this has not been properly explained to you.

I am, very respectfully, your obedient servant,

GEO. B. McCLELLAN,

Major-General, U. S. Army.

HEADQUARTERS ARMY OF THE POTOMAC,
August 30, 1862.

Major General E. V. SUMNER,

Commanding Second Army Corps, Arlington, Va.:

By direction of the general-in-chief you will at once march with all your command, excepting one brigade and a light battery to be left between Chain Bridge and Tennallytown, to the relief of General Pope.

You will take the Columbia pike via Annandale and Fairfax Court-House. Three hundred men on the Excelsior Brigade will join you at Annandale.

Please report the hour of your departure, and take two or three days' rations in haversacks.

GEO. B. McCLELLAN,

Major-General.

P. S. - The detachment of the Excelsior Brigade will not be able to move until late in the day. They are to escort three batteries this afternoon, and will probably join you to-night. These batteries belong to Heintzelman's corps, and the commanding general wishes you to send them to their appropriate command as soon as you can safety do so.

By command of Major-General McClellan:

S. WILLIAMS,

Assistant Adjutant-General.

HEADQUARTERS ARMY OF THE POTOMAC,
Near Alexandria, August 30, 1862. (Received 10.40 a. m.)

Major General H. W. HALLECK, General-in-Chief:

Couch has reached Aquia with a portion of his division, and will soon be here. Please inform me in tome whether your information form up the river and from direction of Dranesville renders it expedient to place him so as to watch in that direction or whether he will be better placed near here. If he is to go toward Tennallytown of Chain Bridge some little time will be saved by landing him at washington of Georgetown. Firing still continues, but less heavily, I think.

GEO. B. McCLELLAN,

Major-General.