HEADQUARTERS CAVALRY CORPS,
May 17, 1863.

Colonel B. F. DAVIS, Commanding Brigade.

(Through Brigadier General A. Pleasonton, Commanding First Cav. Div.):

COLONEL: The major-general commanding directs me to say to you tht there are certain people, either bushwackers or men detached from what is known as the Black Horse Cavalry, who operate on the right of and within our lines. All of whom he wishes you to put out of the way-no matter how, so they are gotten rid of. Communicate with General Gregg, near Bealeton, and he will, if possible, co-operate with you.

Very respectfully, your obedient servant,

J. H. TAYLOR,

Chief of Staff.

POTOMAC CREEK,

May 17, 1863.

Brigadier-General GREGG:

Your dispatch received. Davis has been ordered to co-operate with you in destroying bushwhackers on the right.

J. H. TAYLOR,

Chief of Staff.

HEADQUARTERS DEPARTMENT OF WASHINGTON,

Washington, D. C., May 17, 1863

General H. W. HALLECK, U. S. Army

Commanding, &c., Washington, D. C.,:

GENERAL: I have the honor, in reply to your verbal inquiry of to-day as to how many infantry I can spare from the Defense of Washington for operations beyond the Rappahannock, to state: From the last morning report of the troops in the Defenses of Washington, dated May 10, 1863, the aggregate present amounts to 52,629. Deducting those on special or other duty, sick, and in arrest or confinement, there are only 32,982. In this aggregate are included-first, the troops at headquarters, the reserve or artillery under instruction, and the guards on the railroad from here to Baltimore, 1,530. The garrison of Fort Washington, 118. City guards of Washington and Alexandria, 5,324. Corps of Observation on this side of the Potomac, guarding the river as far as the Monocacy, 1,177. Camps Convalescent and Distribution, 1,177. General J. Stahel's cavalry division, 3,739. Garrisons for the forts from Chain Bridge to Fort Greble 5,329. Garrisons for the south side of the Potomac, from Fort Marcy to Fort Lyon, below Alexandria, 5,988. This leaves but the force under General Abercrombie, including the First Brigade of Pennsylvania Reserves, of 8,581. From this latter force the Pennsylvania Reserves hodl the depot at Fairfax Station, and furnish laborers to load and unload cars, and guards on the railroad. General Abercrombie sends one regiment to picket on the Occoquan, where, on account of the wooded nature of the country, I only use cavalry, and cannot send a wagon to the depot without a strong escort, or it will be captured by the guerrillas. Of the 7,057 men, including this regiment, and excluding the Pennsylvania Reserves under General Abercrombie's command, there are two regiments at Wolf Run Shoals; two regiments at Union Mills, guarding the railroad bridge