It seems to me necessary that our forces concentrate at Gainesville in pursuit of the enemy.

Being almost without cavalry, I beg leave to request you to send me one regiment from Warrenton, as cavalry is the only arm which may be of some avail under these circumstances. I cannot be without cavalry. I have only 150 men. Please send the first regiment you can find.

Let the troops advance at once, because the enemy may throw himself on my advance and we could lose the bridge.

Respectfully, yours,

F. SIGEL,

Major-General.

P. S.-Please take care of my train, which is now at Catlett's Station.

D.

HEADQUARTERS FIRST CORPS, ARMY OF VIRGINIA,
Buckland Bridge, Va., August 27, 1862-8 p. m.

Major-General MCDOWELL, Commanding Third Corps:

The First Corps is in bivouac between Gainesville and Broad Run, with the cavalry beyond Gainesville.

General Milroy captured about 100 prisoners, stragglers of the rebel army. One brigade formed the rear guard, which was driven back by my advance. It seems to me essential that we attack to-morrow, when it would be necessary to know the relations existing between the different commands here, and to know who will be in command in case of a battle if General Pope or yourself should not be here.

Inasmuch s it is said that another force is said to advance from Salem, under command of General Longstreet, and that Jackson's troops are very tired and have used a great amount of ammunition, I think they should be attacked at once at Manassas Junction.

Please inform me where General Cox's command is, and whether there is any hope of his joining me soon.

I am, general, very respectfully, your obedient servant,

F. SIGEL,

Major-General, Commanding First Corps.

THIRTY-THIRD DAY.

COURT-ROOM, COR. FOURTEENTH ST. AND PA. AVE.,

Washington, D. C., December 30, 1862.

The court met pursuant to adjournment. Present, * * *, and Major General FRANZ SIGEL, U. S. Volunteers, the witness under examination.

* * * * *

Question by General MCDOWELL. You state you believe that General McDowell did not give his troops the right direction on the 29th, because instead of attacking the enemy on his right flank, by coming in on our left, his troops, as much as you could see, came in from the rear; that is to say, instead of coming in the direction of New Market he came in the direction of Centreville. You do not know for what reason? do you know that General McDowell's troops did not come by the New Market road?

Answer. I do not know.