WASHINGTON, September 2, 1862.

General R. B. MARCY, Chief of Staff:

GENERAL: I inclose you a copy of the order I have just issued, relinquishing command, &c.

A detailed statement will be sent of troops and positions, but for you present convenience I would state that at the present moment the state of things is this: General D. P. Woodbury is in command of forts and troops from Fort Blenker to Fort Lyon. In Fort Lyon is the Third Battalion New York Artillery and the Twenty-fourth Michigan (raw). In Forts ellsworth, Ward, and blenker is part of Colonel Tyler's regiment.

The other troops assigned to Woodbury are: Engineer Brigade, Colonel Allabach's four regiments, General E. B. Tyler's brigade, Sixteenth Connecticut Regiment (in or near Fort Worth.)

Brigadier General A. S. Whipple commands forts and troops from Four Mile Run northward, including the Chain Bridge. A statement already in the hands of General McClellan gives a list of garrison and troops. The Fifteenth Connecticut is to be added (by your orders), and is now over there. Colonel Doubleday has immediate command at the Chain Bridge, under General Whipple.

The forts and troops of the Potomac are in charge of Colonel Haskin, aide-de-camp. A list of the garrisons and troops is in the hands of the major-general commanding.

I am, very respectfully, your most obedient,

J. G. BARNARD,

Brigadier-General.

HEADQUARTERS ARMY CORPS,
Hall's Hill, September 2, 1862.

General MARCY:

I gain from my pickets the following information in regard to firing in my front this afternoon: A battery supported by cavalry, suddenly appeared on Barnett's Hill and opened fire upon Pleasanton at Falls Church, while dismounted cavalry fired upon and killed 3 of his mounted pickets, who, armed only with sabers and pistols, could not contend with the enemy protected by timber. Pleasonton replied with his battery, but the shots of parties fell very short. The enemy, supposed to have come from direction of Hunter's Mill, returned toward Vienna.

The country beyond our picket lines affords every facility for such surprises, and the commanding general must expect them to be frequent so long as the enemy continues in large force in our front and wishes to divert attention from other movements. From the opposite hills our camp and movements are open view of the enemy.

F. J. PORTER,

Major-General, Commanding.

HEADQUARTERS ARMY OF THE POTOMAC,
September 2, 1862.

Colonel A. V. COLBURN:

Your dispatch, directing that a portion of Pleasonton's command be sent to Fairfax Court-House, has been received, and the necessary in