ROCKVILLE, September 9, 1862-8.40 p. m.

Major General FITZ JOHN PORTER, Arlington:

Dispatch received. Our cavalry have had some handsome affairs today, fully maintaining the morale they gained on the Peninsula. We have regained Barnesville and Sugar Loaf Mountain. The army is tonight well posted to act in any direction the moment the enemy develops his movements. I am now in condition to watch him closely, and he will find it hard to escape me if he commits a blunder. We shall do our best, and I think that will suffice.

GEO. B. McCLELLAN,

Major-General.

LEESBOROUGH, MD,

September 9, 1862-11.45 a. m.

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

The following dispatch from Colonel Devin just received. General Burnside desires me to say that he will order scouts to be pushed out, and ascertain if the enemy's pickets are at Lisbon, and also to go off in the direction of Franklinville, Unionville, and Liberty:

BROOKVILLE, MD., September 9, 1862-8 a. m.

Major-General BURNSIDE:

All quiet as yet this a. m. My pickets are in reserve at Triadelphia and Unity, and scout the country around Cooksville and the turnpike. The enemy is said to have pickets at Lisbon. Captain Beardsley stopped a citizen with a pass dated at Frederick yesterday, and signed by Brigadier-General Lee. It is reported that the enemy is making for Ellicott's Mill, and that they are receiving re-enforcements from Maryland. I give this merely as reports current among citizens about Cooksville. I will send another dispatch as soon as I hear from the front.

THOS. C. DEVIN,

Colonel, Commanding Cavalry.

JNumbers G. PARKE,

Chief of Staff.

LEESBOROUGH, MD., September 9, 1862.

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

The following dispatch just received. We have broken up camp and will move on to the neighborhood of Goshen and Cracklinton:

BROOKVILLE, September 9, [1862].

General BURNSIDE:

I had already sent you a dispatch before the arrival of your message. All is quiet as yet. My pickets are in reserve 6 miles in front of this place, and scout up to Cooksville, and are working the pike at that place. As far as I can learn, all is quiet this side of the railroad, on which the enemy have pickets. My scouts were yesterday to the northeast end west of Cooksville for some miles, but met none of the enemy. We are also watching the front to Lisbon, where the enemy are said to have pickets. I am expecting a report from the front every minute, which I will send as soon as received.

Respectfully,

THOS. C. DEVIN,

Colonel.

P. S.-Have just received report from extreme front. Up to 3 p. m. all quiet. Scouted to Lisbon and Damascus last night. No enemy there. We have pickets now on National road.

THOS. C. DEVIN,

Colonel.

A. E. BURNSIDE,

Major-General.