with Colonel Averell via Diascund Bridge. The squadrons sent out should be placed in positions where they can resist any cavalry force that may threaten them. You will be in position to-morrow at as early an hour as practicable, and receive orders from Colonel Averell. Communicate frequently with the troops at new pontoon bridge at Barrett's Ferry, near mouth of Chickahominy. General F. J. Porter will cross the bridge to-morrow.

Inform General Van Alen that you have been ordered to advance, but give him no particulars of your movements or those of this army.

General Van Alen will be instructed to send you all his cavalry except one squadron.

Regard this dispatch as confidential.

GEO. B. McCLELLAN,

Major-General, Commanding.

GENERAL ORDERS, HDQRS. ARMY OF THE POTOMAC,

No. 155.* Camp near Harrison's Landing, Va., August 14, '62.

1. In the contemplated movement, unless otherwise directed, the train of each division will precede the division, arranged in the order of march of the troops, and will be itself preceded by an advanced guard taken from the division.

The train of the reserve artillery of the corps will go with the train of the leading division.

Each quartermaster and his assistants must be with his train, and require it to take at the proper time its appropriate place in the column and keep it, and will see that his wagons do not check the march of the troops or wagons in the rear.

2. Each regimental commander will be held responsible for delay caused by any wagons of the train of his regiment not being ready. So, too, with each brigade and division commander regarding his supply train. Any train not prepared to move at its appropriate time will be held, to fall in the rear of the division trains.

3. Trains of batteries attached to divisions will accompany that of the division in the order of march.

Corps commanders will designate the order of march of the supply trains.

4. Staff officers not otherwise occupied will find their appropriate place in the line of march, ascertaining the cause of any detention that may occur.

5. On arriving in camp each commander will see to all necessary arrangements, such as requiring wagons to be camped quickly, properly faced, bridges to be made, fences removed, ditches filled, &c., to enable trains to leave and re-enter the road without delay.

6. If troops or artillery are required to pass wagons at any time they will pass on the left, and the wagons will close sufficiently to the right and keep moving if possible. Trains must be kept closed, and must not be cut by other trains, artillery, or troops.

7. During a temporary halt, quartermaster will close up and double or park their trains in convenient places near the road so as to allow rear trains to move up, thus shortening the line occupied by the column.

8. No accident, such as breaking down of a wagon, balking of a team,

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*The following [above] was not published as a general order. It was directed to be considered a circular, without number. General Orders, No. 155, of the series of 1862, bears date September 9.

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