WAR DEPARTMENT,

Washington, September 27, 1862.

Major General JOHN E. WOOL,

Baltimore, Md.:

The Secretary of War directs that you send a regiment of volunteers to Wilmington, to guard powder-mills, in place of Colonel Eakin's regiment of Pennsylvania militia.

H. W. HALLECK,

General-in-Chief.

BALTIMORE, September 27, 1862-9.25 a.m.

General McCLELLAN,

Sharpsburg, Md.:

Last evening I ordered Brigadier-General Kelley, at Cumberland, to report to you for orders, and Colonel Campbell to fall back on Cumberland, if he should be attacked by a large force. He, of course, is subject to your orders.

JOHN E. WOOL,

Major-General, Commanding.

HEADQUARTERS ARMY OF THE POTOMAC,
September 28, 1862-1 p.m. (Received 4.50 p.m.)

Major General H. W. HALLECK:

Heavy lines of dust were seen last evening, extending from Martinsburg toward Winchester, along the turnpike. Whether this was caused by marching troops or the passage of supply trains I have not as yet been able to determine. I shall probably be able to get more information upon the subject to-day.

GEO. B. McCLELLAN,

Major-General.

HEADQUARTERS ARMY OF THE POTOMAC,
September 28, 1862-10.30 p.m. (Received 11.25 p.m.)

Major General H. W. HALLECK,

General-in-Chief:

Several reports have been made to me this evening that the main rebel army is retreating from the vicinity of Martinsburg in the direction of Winchester. I shall send out strong reconnaissance in the morning to test the truth of these reports.

GEO. B. McCLELLAN,

Major-General, Commanding.

FAIRVIEW, MD.,

Via Chambersburg, Pa., September 28, 1862-6 p.m.

Major General GEORGE B. McCLELLAN,

Sharpsburg, Md.:

The enemy has fallen back from Martinsburg, toward Winchester, about 10 miles. Their camp is near Bunker Hill and Darkesville.

W. W. ROWLEY,

Lieutenant and Acting Signal Officer.