HEADQUARTERS SECOND CAVALRY DIVISION, Martinsburg, W. Va., August 17, 1864.

Brigadier General J. D. STEVENSON,
Commanding District of Harper's Ferry:

GENERAL: By direction of General Averell I have the honor to acknowledge the receipt of your note of yesterday, reporting the presence of 500 or 600 guerrillas at Charlestown, and directing him to take 1,000 men, with two pieces of artillery, "to clean them out." I am instructed to say, in reply, that this command, having been almost constantly upon the march since the 1st of May, has been halted here to remount and refit. General Averell considers it unnecessary and improper to march 1,000 of his men with two pieces of artillery against 500 or 600 guerrillas. His scouts have already informed him of the presence of these predatory bands in the vicinity of Charlestown, and that General Duffie, with his division, was last evening at Berryville for the purpose of keeping that flank clear. Two hundred men have been sent from this division to communicate with General Duffie and to disperse the guerrillas in the vicinity of Charlestown. I am directed to request that you will be good enough to furnish General Averell with any information that you may obtain of the enemy and his movements.

Respectfully, your obedient servant,

WILL RUMSEY,

Assistant Adjutant-General.

HARPER'S FERRY, August 17, 1864.

General AVERELL:

Mosby, White, and other bands of enemy are concentrated in vicinity of Charlestown, with view to attack trains and cut off all couriers. Yesterday evening and last night they were in Charlestown. Have you sent any portion of your command to Charlestown? We have large trains to be sent forward, but there is no safety with such guards as I can furnish, unless Charlestown is held with force sufficient to scout country and clear road of guerrillas.

JOHN D. STEVENSON,

Brigadier-General.

MARTINSBURG, August 17, 1864.

Brigadier-General STEVENSON:

General Duffie's division was at Berryville yesterday evening. Two hundred of my command have been sent to communicate with him and to capture, kill, or disperse the guerrillas at Charlestown. They should have arrived there before this. I have also scouts in that direction. If they do not succeed in clearing out the place I will send more. There should be a strong picket at Keyes' Ford, which would hinder the enemy. Please inform me if you hear from Charlestown before I do.

WM. W. AVERELL,

Brigadier-General.