ARLINGTON HOUSE, VA., March 29, 1864--10. 30 a. m.

Colonel J. H. TAYLOR,

Headquarters, Washington, D. C.:

I have the honor to forward a communication from Colonel Piper, commanding Third Brigade, Fort Lyon, just received at these headquarters. There is no cavalry in this division except on the extreme right--a detachment of the Thirteenth New York--and presume that they would not be likely to be in the position referred to by Colonel Piper, which is as follows:

SIR: My pickets reported on yesterday that a party of mounted men (about 15 in number) were seen in a direction southwest from Fort Lyon and about half a mile distant. I presume this t have been a party of our cavalry, as it is hardly probable that a marauding party of the enemy would show themselves so publicly. I respectfully request that I may be informed if we have any cavalry pickets in front of my lines.

I am, very respectfully, your obedient servant,

A. PIPER,

Colonel Tenth New York Artillery, Commanding Brigade.

G. A. DE RUSSY,

Brigadier-General of Volunteers.

HEADQUARTERS DEPARTMENT OF WEST VIRGINIA,
Cumberland, Md., March 29, 1864.

Brigadier-General THOMAS,

Adjutant-General U. S. Army, Washington:

GENERAL: For the purpose of general information to the War Department and the general commanding the Army, I have the honor to submit the following report in regard to the strength, position, and condition of the troops in this department, with some additional remarks pertaining to this subject:

First. The Department of West Virginia extends from the Potomac in the east to the Ohio and beyond the Kanawha in the west and southwest, and includes the whole line of the Baltimore railroad from the Monocacy and Harper's Ferry to Parkersburg and the Northwestern Railroad from Grafton to Wheeling. These lines must be protected, not only on account of their importance as public highways, but also on account of their importance and necessity as lines of communication and supplies for the Army of West Virginia. To effect this, the larger portion of the troops belonging to this department are distributed from monocacy to Fredericktown and Harper's Ferry to Parkersburg and Wheeling.

Second. The forces now present for duty and equipped, according to last tri-monthly report of 20th of March, are: Infantry, officers and men, 15,680; cavalry, officers and men, 5,441; artillery, officers and men, 2,276; total, 23,397.

Subtract Wheaton's brigade, ordered to the Potomac, about 1,000 for duty and equipped, which would make an aggregate present and equipped 22,397.

There are 118 pieces of artillery in this department; of these, thirty are siege guns, and thirteen unmounted pieces in fixed positions. The eighty-six field pieces remaining are distributed as follows: With General Sullivan at Harper's Ferry and Martinsburg, thirty pieces; with Colonel Mulligan, twenty-two pieces; at Cumberland, New Creek, Burlington, and Greenland Gap, and at Clarksburg, with