HEADQUARTERS CAVALRY BRIGADE, Purcellville, October 31, [1862]-2 p. m.

General BAYARD, Commanding Cavalry:

GENERAL: A dispatch from General McClellan, dated 10.30 this morning, says:

The general would like to have a cavalry reconnaissance in force with your command and mine united, for the purpose of ascertaining where the enemy is in force, and which direction he is moving, but he did not desire to have a battle brought on. Should you, however, find a force of the enemy's cavalry in such position that you can attack to advantage, of course you authorized to do so, without running any great risk to your own command. General Bayard should wait in the vicinity further orders before going back toward Washington.

Shall we make an attempt at Snickersville, or do you think we would do better by going toward Ashby's Gap? My aide will tell you my strength, form which you can judge, with yours, what we can do.

I am, general, very respectfully,
A. PLEASONTON,

Brigadier-General, Commanding.

[Indorsement.]

HEADQUARTERS, Near Chantilly, November 1, 1862.

Above dispatch received at 3.30 p. m. to-day. General Pleasonton's aide supposes the firing to be General Pleasonton engaging the enemy. General Pleasonton intends to have his headquarters at Philomont to-day. He will have about 1,000 men and a horse battery of six 3-inch guns, with which to co-operate with you. General Pleasonton's aide will wait for an answer until to-morrow morning.

S. R. COLWELL,
Aide-de-Camp.

HEADQUARTERS DEFENSES OF WASHINGTON, October 31, 1862.

Lieutenant Colonel CHAUNCEY McKEEVER,

Assistant Adjutant-General, Arlington:

Direct General Sickles to have his division prepared to march to-morrow morning with two days' rations in haversacks, and five more, in wagons, to follow. More detailed instructions will be sent by an orderly.

S. P. HEINTZELMAN,

Major-General, Commanding.

HEADQUARTERS ARMY OF THE POTOMAC, October 31, 1862-10.30 p. m. (Received 11.45 p. m.)

Brigadier-General HAUPT,
Superintendent Military Railroads:

The commanding general directs me to say to you that he has no information that the brigade across Goose Creek has been destroyed, but he desires you to be prepared with material for reconstructing the bridge on the Manassas Gap Railroad, if it should become necessary. He also wishes you to have your rolling stock prepared to throw forward supplies rapidly on this road. Please consult General Heintzelman.

R. B. MARCY,

Chief of Staff.