ALEXANDRIA, September 23, 1864. (Received 9.40 p. m.)

Colonel D. C. McCALLUM:

My assistant, sent to examine the Manassas Gap road, has returned, 9.15 p. m. He went to Falls Church and reported to Colonel Lazelle, who said he had not a sufficient force to go beyond White Plains, and would have to send to Washington before starting. He is to notify me when ready.

E. L. WENTZ.

HEADQUARTERS CAVALRY, BRIGADE, Near Fort Buffalo, Va., September 23, 1864.

Lieutenant Colonel J. H. TAYLOR,
Chief of Staff and Assistant Adjutant-General:

COLONEL: I have the honor to inform you that there is nothing of importance to report from this vicinity. A force of 200 men sent up the country south of Aldie last night to look for Mosby at Doctor Ewell's house has not yet returned. It is expected in to-night.

Very respectfully, your obedient servant,

H. M. LAZELLE,

Colonel Sixteenth New York Cavalry, Commanding Cavalry Brigade.

HEADQUARTERS CAVALRY BRIGADE, Near Fort Buffalo, Va., September 23, 1864.

Lieutenant Colonel J. H. TAYLOR,
Chief of Staff and Assistant Adjutant-General:

COLONEL: In reply to your communication of this date, concerning the escort to be furnished to an engineer to be sent examine the Manassas Gap Railroad, I have the honor to inform you that I have communicated with the engineer sent, and have informed him that in my opinion it would be extremely hazardous to send a force of 350 men farther than the vicinity of Piedmont, and that a greater force than that cannot be spared from here with present dispositions. Even under these circumstances a portion of the picket-line would have to be removed . He states that he desires to examine the railroad to Strasburg. I have postponed all action awaiting your reply, and have informed of military railroads at Alexandria, Mr. E. L. Wentz.

Very respectfully, your obedient servant,

H. M. LAZELLE,

Colonel Sixteenth New York Vol. Cavalry, Comdg. Cavalry Brigade.

HDQRS. DEPARTMENT OF WASHINGTON, 22ND ARMY CORPS, Washington, D. C., September 23, 1864-10.15 p. m.

Colonel LAZELLE,
Commanding Cavalry Brigade, Falls Church, Va.:

Send the escort, and make it as strong as you deem necessary. I will send you other men to make your line good. Let me know the number your require. I will return the companies at either Ethan Allen, Fort Reno, or at Alexandria. Will that be sufficient?

Respectfully, yours,

C. C. AUGUR,

Major-General, Commanding.