just returned, with 1 prisoner and 2 horses of Fifth Virginia Cavalry. The reports are not true. The prisoner's regiment is ordered to reassemble at Orange Court-House, April 1, and nearly all have gone. Roads bad.

I. J. WISTAR,

Brigadier-General.

Major-General BUTLER.

MARCH 28-29, 1864. - Scout to Aldie and Middleburg, Va.

Report of Colonel Joseph W. Fisher, Fifth Pennsylvania Reserves.

HDQRS. 3rd Brigadier, PENNSYLVANIA RESERVE CORPS,
March 30, 1864.

SIR: I have the honor to report the result of a somewhat extensive scout from which I returned last night, and in making this report I attach no importance to the scout itself beyond information obtained, which I think of some importance to the Army of the Potomac and the Government.

I left my headquarters at 10 p. m. of Monday, 28th instant, with 225 men of the Thirteenth Pennsylvania Cavalry, under the command of Major McCabe, crossing the Bull Run battle-field, striking the Alexandria and Warrenton turnpike about 1 1/2 miles east of Groveton. Passing up the pike to Groveton I took the road to Sudley Mills, and from thence direct to Aldie, which place I reached at 5 a. m. of the 29th. I made careful searches of all the houses and other buildings where I though guerrillas of all the houses and Aldie I obtained some important information as to the extent of Colonel Mosby's command, and also to his location. I then pushed rapidly forward to Middleburg, where I had previously learned Mosby had his advance, but before we reached that point the enemy had retired. Not deeming it safe to go farther through those mountain passes with my small command (having learned from undoubted authority that Mosby had nearly three times my number), I returned to Aldie and rested my command for some time. I had not been long at the latter place until my pickets reported the enemy advancing in considerable force and attempting to surround and cut us off. I at once started with one company of cavalry back the turnpike in the direction of Middleburg, driving the enemy before me until they reached a hill 2 miles beyond Aldie, where they were in considerable force. My pickets reported to me at this point that two columns of the enemy were marching down on my right flank, evidently with the intention of getting into my rear. I endeavored to bring those in my front to a fight but failed to do so, except by the exchange of a few shots, none of which took effect so far as I know, and as I advanced they fell back, probably trying to lead me into an ambush. I then withdrew, following down the Little River turnpike until I struck the Sudley road, and from thence back to my headquarters, which I reached at 5 p. m. of yesterday after a march of 65 to 75 miles. From all I have learned I have come to the conclusion that we have not sufficient cavalry force attached to the division to drive Mosby out of the country, but that a simultaneous movement from Bristoe or Manassas and Warrenton would effect that object.