HARPER'S FERRY, W. VA., July 21, 1863.

Major General H. W. HALLECK,

General-in-Chief:

Captain J. E. Smith has arrived here with his battery-the Fourth New York-en route for the Third Army Corps. The army having left, and being some 40 miles ahead, Captain Smith desires further orders. It is not safe for him to go across, nor have I a proper cavalry escort. Will you please indicate your wishes as to this battery?

HENRY H. LOCKWOOD,

Brigadier-General, Commanding Maryland Heights.

Headquarters, Baltimore, July 21, 1863-3 p. m. (Received 3. 10 p. m.)

Major-General HALLECK,

General-in-Chief:

Under your order, received by telegraph, authorizing and regulating the seizure of horses in disaffected regions, Colonel Sangster, in charge of parole camp at Annapolis, was ordered to mount two companies of cavalry to guard his camp, and do patrol duty, as all his force had been sent to aid General Meade in Pennsylvania.

ROBT. C. SCHENCK,

Major-General.

SPECIAL ORDERS, HDQRS. DEPT. OF THE MONONGAHELA,

Numbers 17.
Pittsburgh, Pa., July 21, 1863.

I. It being necessary to occupy Camp Howe as a rendezvous for drafted men, Colonel J. B. Kiddoo is hereby relieved from the command. The general commanding desires to express his thanks to him for the prompt and efficient manner with which he has discharged the duties as commandant of the camp.

* * * * *

By command of Major-General Brooks:

[T. B. SWEARINGEN,]

Assistant Adjutant-General.

CIRCULAR.] HEADQUARTERS ARMY OF THE POTOMAC, July 22, 1863.

The following movements of troops are ordered for to-day, and will be made immediately upon receipt of this order: The Third Corps will move to Piedmont, and take a position in that vicinity, looking to Manassas Gap, with a view to supporting the cavalry now in that Gap, and maintaining possession of it, if practicable. Should the cavalry still hold the Gap when the Fifth Corps reaches Piedmont, General French will throw forward a division in support. The Fifth Corps will move to Rectortown, and support the Third Corps, if necessary. The First Corps will move to White Plains, prepared to move to the support of the Third and Fifth Corps.