WASHINGTON, D. C., April 4, 1864.

Major General Q. A. GILLMORE,

Department of the South:

GENERAL: Lieutenant-General Grant Directs that you move with all possible dispatch so much of your forces as in your judgment can be safely spared from the Department of the South to Fort Monroe, Va., and report to Major General B. F. Butler, who will have orders in regard to your future operations. You will turn over the Department of the South and the troops which you may deem necessary to leave there to Brigadier General J. P. Hatch. You will be joined at Fort Monroe by the regiments and fractions of regiments belonging to the Department of the South which have been on furlough at the North, and are now rendezvousing here preparatory to their return to your command. The troops which you bring with you and those which join you at Fort Monroe will constitute the Tenth Army Corps. You will bring with you their arms, baggage, and transportation. Fractional portions now North of such regiments as you may leave in the Department of the South will be sent by you from Fort Monroe to their proper commands in the South. Of course the arms, baggage, &c., of such parts of organizations will not be brought north. The selection of the troops to be brought north for active operations in the field is left entirely to your own judgment. The lieutenant-general, however, expects from your own reports that your effective command on its arrival at Fort Monroe will be from 7,000 to 11,000 men. This corps, increased by such forces as we may be able to give it, will commanded by you in the field. General Grant hopes that your command will reach Fort Monroe by the 18th instant; if not by that time, as soon thereafter as possible. The troops should arrive ready in every respect for the field. Apply to Major-General Butler for such supplies as you may require. Should he not be able to meet your requisitions, telegraph immediately on ascertaining that fact to the proper department in Washington.

The Twenty-sixth U. S. Colored and the Twenty-ninth Connecticut Colored Regiments will be immediately sent to the Department of the South. They number about 900 each. Possibly another colored regiment will be sent to that department, but do not rely on it. General Meigs is collecting vessels to assist in bringing up your forces and their transportation.

Very respectfully, your obedient servant,

H. W. HALLECK,

Major-General, Chief of Staff.

GENERAL ORDERS,
HDQRS. ARMY OF THE POTOMAC, Numbers 15. April 5, 1864.

I. The organization of the provost-marshal's department of this army will be as follows:

First. At army headquarters the officers and guards at present authorized.

At army corps headquarters a provost-marshal having the rank of field officer, assisted by a captain or lieutenant, and such guards as in the judgment of the corps commander may be necessary for the efficient working of the department.

At division headquarters a provost-marshal having the rank of