HEADQUARTERS ARMY OF THE POTOMAC,
Camp near Rockville, Md., September 10, 1862-12.30 p. m.

(Received 2 p. m.)

Major General H. W. HALLECK,

General-in-Chief:

For reply to your dispatch of 10 a. m., please see my dispatch of 12 m. to the President, in reply to his of to-day. It gives at length all the information I have that has not already been sent you.

GEO. B. McCLELLAN,

Major-General.

WASHINGTON, D. C. September 10, 1862.

(Sent 4 p. m.)

Major-General McCLELLAN, Rockville, Md.:

Three good regiments have arrived from Suffolk. Had they not better be united with some new regiments as a reserve brigade, near Tennallytown or some other point, instead of sending them immediately into the field?

H. W. HALLACK,

General-in-Chief.

BROOKVILLE, MD., September 10, 1862-8 p. m.

(Received 8.50 p. m.)

Major-General HALLECK:

General Burnside has an advance guard at Damascus; 5,000 men at Goshen and Seneca Bridge; 4,000 at Cracklinton. Hooker's command is in the vicinity of Brookville. I cannot learn that there is any large force of the enemy's infantry this side of the Monocacy. I think there is little indication of the enemy's advancing either on Baltimore or York. I shall probably get positive information to-morrow.

GEO. B. McCLELLAN,

Major-General.

BROOKVILLE, MD., September 10, 1862-11.55 p. m.

(Received September 11, 12.10 a. m.)

Major-General HALLECK:

I have ordered a general advance to-morrow. Send me up all the troops you can spare.

GEO. B. McCLELLAN,

Major-General.

HEADQUARTERS ARMY OF THE POTOMAC,
Camp near Rockville, Md., September 10, 1862-3.30 a. m.

Major-General BANKS:

The disposition of troops here to-day is such as to uncover Washington slightly in the direction of Baltimore. Put both your troops and works on this side of the river in good condition for defense.

By command of Major-General McClellan:

R. B. MARCY,

Chief of Staff.