HDQRS. THIRD ARMY CORPS, ARMY OF VIRGINIA, August 26, 1862.

Brigadier General J. B. RICKETTS,
Commanding Division:

GENERAL: Information received this morning indicates the enemy has passed through White Plains and Thoroughfare Gap and that his troops are moving constantly in that direction, so that we have them on three sides. Your position becomes one of very great importance, and the mountain on the right of the position, which is, as the general understands, now occupied by General Tower, is one which the general wishes you and General Tower to examine particularly in the morning.

General Buford will send out to-night parties of cavalry which will cover your entire front. Examine all the ground occupied by your entire division,a nd have a little sketch of it prepared as soon a you can.

Very respectfully, your obedient servant,

ED. SCHRIVER,

Colonel and Chief of Staff.

HDQRS. THIRD ARMY CORPS, ARMY OF VIRGINIA, August 26, 1862.

Brigadier-General BUFORD,
Commanding Cavalry:

GENERAL: You will take your position as ordered yesterday, on the Waterloo road, near the Waterloo Bridge. It is greatly desired by Major-General Pope to know what force the enemy has opposite Waterloo Bridge, and what direction the head of his column has taken, whether toward Luray, Chester Gap, or Rectortown. Use every effort to ascertain this by the employment of scouts, spies, and reconnaissances. Use money freely to pay for it.

Report to me on the receipt hereof which regiments you have with you and where they are posted.

Very respectfully, your obedient servant,

S. F. BARSTOW,

Assistant Adjutant-General.

HDQRS. THIRD ARMY CORPS, ARMY OF VIRGINIA, August 26, 1862.

Brigadier General RUFUS KING,
Commanding Division:

GENERAL: The reconnaissances at Waterloo and Rappahannock having failed, you will not push any part of your division across the river, but take up the best position on this side, out of cannon-range, avoiding useless cannonading.

Rickett's division goes across to Waterloo road; make, therefore, disposition of your bridges without regard to him; place one brigade in advance, two in line in rear of it, and the fourth as a reserve in rear of main line. Bayard's cavalry ought to be joining you very soon. Let me know when it arrives.

My headquarters are in camp just out Warrenton, on Sulphur Springs road.

By order of Major-General McDowell:

ED. SCHRIVER,

Colonel and Chief of Staff.