WASHINGTON, September 15, 1862.

Major-General BANKS, Commanding, &c.:

GENERAL: Please send a division of old and new troops as a guard to the crossings between Great Falls and Point of Rocks. The main body should take some central position, so as to act, as circumstances may require, on either of the fords-say at Dawsonville or Poolesville, the point to be selected by the commander. I recommend Brigadier-General Stoneman for this command.

Very respectfully, your obedient servant,

H. W. HALLECK,

General-in-Chief.

ARLINGTON, September 15, 1862-12.25.

General HEINTZELMAN:

Colonel Davies, commanding cavalry brigade, proposes to send this afternoon ten companies of cavalry and a section of artillery to Aldie Gap, on Bull Run Mountain, four companies to proceed toward Snicker's and Ashby's Gaps, to intercept the enemy's supply train for Winchester. Aldie is about 30 miles from Upton's Hill, and the scouting party would go about 10 or 12 miles farther. The expedition should start this afternoon and be back by to-morrow night. Colonel Davies thinks much information might be gained, many stragglers taken, and it would favor of our forces at Harper's Ferry.

CHAUNCEY McKEEVER,

Chief of Staff.

HEADQUARTERS DEFENSES OF WASHINGTON,
September 15, 1862-12 m.

Major General S. P. HEINTZELMAN, Arlington:

The General-in-Chief directs General Banks to send a division of old and new troops to guard the crossing from Great Falls to Point of Rocks, and recommends General Stoneman for the command. General Banks is inclined to think it best under this order to give General Stoneman one brigade of his own division, or two, if necessary, and a brigade of new troops, including the Thirty-ninth Massachusetts and Tenth Vermont, already up the river. He desires to have your views. Has General Stoneman joined? Please answer immediately.

RICH'D B. IRWIN,

Captain, Aide-de-Camp, and Actg. Asst. Adjt. General

HEADQUARTERS DEFENSES OF WASHINGTON,
September 15, 1862-2 p. m.

Major General GEORGE B. McCLELLAN,

Bolivar, Three Miles beyond Middletown:

Your telegram of 9 a. m. received 1.30. I congratulate you upon your great success. By direction of the General-in-Chief, General Stoneman is ordered to proceed at once to the Upper Potomac with six regiments of his division, and also to take command of two new regiments and a battery sent up last night, for the purpose of guarding the crossings