MARYLAND HEIGHTS, July 8, 1864.

(Received 12.45 p. m.)

The enemy's forces who were in our front at harper's Ferry have withdrawn during the night. Their rear guard is in sight of one of our brigades, which is following them toward Sharpsburg. It seems that the main force of the enemy are taking the road to Boonsborough. Our cavalry from this place is now at Antietam Creek. Yesterday the enemy made preparations for a general attack on our northern line, and tried to bring his artillery in position. Was unable to do so on account of field batteries and heavy pieces in the forts, which shelled their artillery, infantry, and trains for a distance of four miles. General Stahel has orders to follow the enemy's movements from Pleasant Valley toward Boonsborough. He is engaged with them. We have taken possession of Harper's Ferry. Prisoners captured confirm the report heretofore sent as to the number of the enemy.

F. SIGEL,

Major-General.

ADJUTANT-GENERAL U. S. ARMY.

MARYLAND HEIGHTS, MD., July 8, 1864-1 p. m.

(Received 3 p. m.)

The following just received from General Stahel, in Pleasant Valley: "The enemy is advancing in strong force, said to be a whole corps, in the Middletown Valley." A few minutes ago I sent a report from Harper's Ferry stating that our advance from Maryland Heights is at Antietam Creek. According to all information which has been received it seems certain that the enemy with his whole force is marching for Frederick. Prisoners from the enemy agree in the statement in regard to the composition of the rebel army as previously reported.

F. SIGEL,

Major-General.

ADJUTANT-GENERAL U. S. ARMY.

Numbers 2. Report of Lieutenant Amos M. Thayer, One Hundred and twelfth New York Infantry, Acting Signal Officer, of operations about Harper's Ferry July 3-14.

HEADQUARTERS SIGNAL DETACHMENT,
Maryland Heights, July-, 1864.

CAPTAIN: I have the honor to make you the following report of the operations of this detachment during the recent investment of this place and the raid through Maryland:

The detachment with which I reported here during the latter part of June consisted of fifty-eight enlisted men and two officers, including myself. These men, with an exception, were recruits who had seen no active service and were of necessity inexperienced in everything pertaining to the operations of a signal party in the field.