WASHINGTON, D. C.,

September 21, 1862. (Sent 1.20 p. m.)

Major-General MCCLELLAN:

Your telegrams of 8 a. m. and 11 p. m. yesterday are just received. General Banks had anticipated the order you suggest. The Government has been most anxious for the last two days to obtain the information given in yours of yesterday morning, just received, and you have entirely miscontrued the urgency of my request for it. Except your short dispatch, in regard to Pleasonton's pursuit, I had no official information of what had taken place since the battle of the 17th.

H. W. HALLECK,

General-in-Chief.

CAMP NEAR THE POTOMAC - 10 a. m.,

Via Frederick, Md., September 21, 1862 - 6.45 p. m.

(Received 8 p. m.)

Major General H. W. HALLECK,

General-in-Chief:

Re-enforcements were sent last night to General Couch, at Williamsport. No news has been received from there since 11 p. m. yesterday, when the enemy were still there. They yet remain at Shepherdstown in some force. Some firing is going on; I think it only their rear guard. It is still quite foggy, and we can tell better when it clears away.

GEO. B. MCCLELLAN,

Major-General, Commanding.

HEADQUARTERS ARMY OF THE POTOMAC,
September 21, 1862 - 5 p. m. (Received 9.15 a. m., 22d.)

Major General H. W. HALLECK,

General-in-Chief:

I propose to send a regiment of cavalry to Cumberland, and thence to Romney and south of that place, in order to ascertain if any of the rebel force recently before it is moving toward Western Virginia. In this connection it is important for me to know as soon as possible what force we now have guarding the Baltimore and Ohio Railroad from Martinsburg west toward Wheeling. Will you do me the favor to answer this at the earliest practicable moment?

GEO. B. MCCLELLAN,

Major-General.

SHARPSBURG, September 21, 1862.

(Received 8 p. m.)

General M. C. MEIGS,

Quartermaster-General:

It is probable that this army must have its main depot at or near Harper's Ferry, provided it remains at all in this section of country after the enemy has left it entirely. We are more than 20 miles from the Frederick and 15 from the Hagerstown depots. The country here on both sides of the Potomac is exhausted of all supplies. It would be found impracticable to supply so large an army beyond the river with wagons. I presume that General McClellan will shortly reach the