WAR DEPARTMENT,

Washington, August 10, 1862.

Major-General BURNSIDE, Falmouth, Va.:

The enemy has attacked General Pope at Culpeper Court-House. Are you ready to co-operate with him? Give me full information of your position and preparation.

H. W. HALLECK,

General-in-Chief.

FALMOUTH, VA., August 10, 1862-11.20 a. m.

Major General H. W. HALLECK:

The last of General King's command left here early this morning. At the request of General Pope I sent with General King two of the best batteries and the Harris Light Cavalry, retaining but one cavalry regiment here of between 400 and 500 men. The New York cavalry regiment which has been guarding the ford on the Rappahannock have been ordered to report to me, but I shall not be able to withdraw them from their present duty. Both of these cavalry are armed with pistols only. Can I not have carbines for them? All is quiet in this neighborhood this morning.

A. E. BURNSIDE,

Major-General.

FALMOUTH, VA., August 10, 1862.

General H. W. HALLECK,

General-in-Chief, Washington:

My letter of yesterday gave you the strength of my force. Six infantry regiments are on the Fredericksburg side, twelve on the Falmouth side, and one guarding the railroad; one cavalry regiment on picket duty south of Fredericksburg, and the other guards the fords between here and Rappahannock Station. I have one good Rhode Island battery, two inferior batteries, and one and part of another that have just arrived from Cloud's Mills that I know nothing of. The Harris Light Cavalry and the two best batteries went with General King this morning. Enough transportation has arrived to carry three days' provisions and 40 rounds of ammunition, leaving tents and all surplus baggage behind. No ambulances or hospital wagons. We lack some canteens, haversacks, and other equipments that have been required for, and which have been promised to leave Washington to-morrow. We tried to get these at Fort Monroe but could not, the wants of the Army of the Potomac were so urgent. These wants will not necessarily prevent our starting our advance at six hours' notice.

If it becomes necessary to move in support of General Pope, I would suggest that Fredericksburg be evacuated, the bridges over the Rappahannock be burned, the sick, surplus baggage, and tents be sent to Aquia Creek, to be loaded in schooners at that place, and order the gunboat here to that point, leaving but a small guard at the depot there, that could embark at once on the approach of the enemy, having first destroyed the Government property. We can then move with the whole force up the north bank of the Rappahannock, striking the railroad at Rappahannock Station, where we will be in position to assist General Pope in case of emergency.

Should we remain here and General Pope defeat the enemy, if deemed