ALEXANDRIA DEPOT. Va., August 2, 1863. (Received 6. 05 p. m.)

Hermann Haupt,

Brigadier-General:

I do not know fully, perhaps, the protection to out road between Alexandria and Manassas, but I deem it proper to state that in my opinion it is not adequate. Aside from trains with their stores and officers of all grades in transit, paymasters with large amounts of money are traveling, and three of these later have gone up to the army to-day. I have heard occasionally of our cavalry scouts near the line. Twice during the past week some were in camp at Accotink for the night, but the first force is a small number of infantry at Burke's, of which 4 or 6 men foot it nightly to Accotink Bridge, and return in the morning. At our wood pile this side of Burke's, we have no protection, and the 60 contraband choppers sleep in the woods, with their own pickets out, and are with difficulty kept at work. Meanwhile 150 guerrillas are in the pine thickets, east of the line at Burke's, watching their chance. I have obtained this information from undoubted authority, and I have no doubt Mosby, the other night, was coming at our line when he accidentally ran across the sutlers, which changed his plan. One thing is sure, and that is every man within 10 miles of our road should be secured, and not released every hour from the Old Capitol on oath of allegiance. To the contrary notwithstanding, 6 rebels were one night the past week at Mrs. Fitzhugh's, near our rad.

J. H. Devereux.

HEADQUARTERS FIRST DIVISION CAVALRY, August 3, 1863-9. 30.

Colonel Alexander,
Chief of Staff, Cavalry Corps:

This morning at & o'clock positive reports were received from my extreme pickets that the enemy were advancing down the railroad in force-cavalry, artillery, and infantry. The division was put in fighting trim, and moved to the front. About a mile and a half to the front, I found a remarkably strong cavalry picket line. Two battle-flags were seen at what I supposed to be the picket reserves. The force reported to have been seen in motion, if true,,, came down the river, and passed to my left toward Kelly's. I do not believe any large force has been in view, although the young officer says positively he saw four or five regiments of cavalry, artillery, and infantry. I have sent out scouting parties in all reasonable directions. I have come back to my old ground, and am prepared to fight to hold it, if necessary. I apprehend no trouble.

Very respectfully,

JNO. Buford,

Brigadier-General of Volunteer, Commanding.

AUGUST 3, 1863-10. 30 a. m.

Major-General Slocum,

Commanding Twelfth Corps:

I am instructed by the major-general commanding to say that the information brought ba General Buford's command shows the enemy