AUGUST 20, 1864.

Captain B. F. FISHER,

Chief Signal Officer, Headquarters Army of the Potomac:

Rebel message received as follows:

Colonel B[RENT],

Assistant Adjutant-General:

As soon as fog cleared up observed unusual activity, from I supposed movements had been taking place. One regiment of infantry in old camp in open space to our left of Cobb's. Three companies of cavalry just crossing pontoon from Chestefield. Six pieces of artillery, with eight horses to each, and sixteen wagons crossed, going in the same direction. Eight ambulances passed Broadway road going toward City Point. Stragglers constantly crossing pontoon going toward Petersburg. Heavy works at the end of Gilliam's farm have been manned.

OPERATOR at C.

(Same to A. B.)

Very respectfully,

THOS. H. FEAREY,

Second Lieutenant.

CIRCULAR.] HEADQUARTERS ARMY OF THE POTOMAC,

August 20, 1864 - 2.30 p. m.

The following project for the disposition of the three corps, in accordance with communicating received from the lieutenant-general commanding armies in the field, is sent for your information and guidance:

1. Major-General Hancock will withdraw from Deep Bottom to-night and reach the vicinity of his former camp toward noon to-morrow, when, with his corps, he will hold the intrenchments now held by Mott's division and extend from the plank road toward the Weldon railroad, in the direction of the position held by the Fifth Corps on that road, and intrench strongly, slashing wherever it can be done.

2. Major-General Parke, commanding Ninth Corps, will withdraw Ferrero's division to-night from the redoubts and trenches, where it is now held in support of Mott's division, and mass it in rear until the same are occupied by General Hancock's troops, when, with his corps, he will hold on Hancock's left, as far toward the Fifth Corps as practicable, strengthening his position by intrenchments, slashing, &c.

3. Major-General Warren will occupy the remainder of the line to the Weldon railroad and the left of the army covering that road, and will strengthen his position by every means in his power.

4. The line from the plank, road to the Weldon railroad need not be pushed up against the enemy's works, but will be established by the corps commanders on the best ground for holding between the intrenchments on the plank road and the position where the left must rest on the Weldon railroad.

5. The remainder of Gregg's cavalry will be moved from Deep Bottom to-night, and the cavalry now with the army will picket on its left and rear and cover the operation of destroying the Weldon railroad.

6. So far as it can be done consistently with the security of his present position and operations, General Warren will have such parts of the intrenchments and slashing made on the lines indicated as he may find practicable.

A. A. HUMPHREYS,

Major-General and Chief of Staff.