HDQRS. DEPARTMENT OF WEST VIRGINIA, Cumberland, Md., December 8, 1863.

Brigadier-General SULLIVAN,
Harper's Ferry:

You will order your available cavalry force, with two regiments of infantry and a battery, to move up the Valley of the Shenandoah on Thursday, the 10th instant, with fifteen days' rations of hard bread, sugar, coffee, and salt, and cattle on the hoof, sheler-tents, plenty of ammunition, but no extra or unnecessary baggage.

Will proceed by easy marches to Strasbrug, where the force will remain till the 17th instant, when it will move forard,if Imboden retires, to Woodstock, and thence to Mount Jackson, New Market, adn Harrisonburg, occupying the latter place on the 20th and 21st and threatening Staunton with cavalry. On the 22d, the force will take up the line of march and return to camp.

B. F. KELLEY,

Brigadier-General.

CUMBERLAND, MD., December 8, 1863 - 4 p.m.

(Received 8.45 p.m.)

Brigadier General G. W. CULLUM,

Chief of Staff:

Brigadier-General Averell left New Creek this morning with three regiments of cavalry and a battery, for the Virginia and Tennessee Railroad. He will proceed via Petersburg, Franklin, Monterey, Covington, and Fincastle, and strike the railroad in Botetourt and Roanoke Counties. Brigadier-General Scammon will also move from the Kanawha to-day, on Lewisburg and Union, for teh purpose of threatening the enemy and the railroad near New River, engaging his attention and making a diversion in Averell's favor. Brigadier-General Sullivan will move a force up the valley via Winchester, Strasburg, Woodstock, &c., threatening Staunton, and engage the attention of Imboden, and prevent him from sending a force against Averell.

Lee may possibly send a mounted force when he learns of this movement, from his left, for the purpose of cutting Averell off; but this, if attempted, I hope will be frustrated by corresponding movements of General Meade's cavalry. If my plans and orders are promptly and faithfully executed, I hope to accomplish important results. It will certainly cut off all communication by railroad and telegraph between Lee and Longstreet.

B. F. KELLEY,

Brigadier-General.

WARRENTON, December 9, 1863.

H. C. WEIR,

Captain, Assistant Adjutant-General:

CAPTAIN: I sent one squadron to Fayetteville about 11 a.m. to-day, with instructions to scour from Fayetteville to and along Warrenton Rairload. The officer has just returned, and reports no enemy in that locality. Will the 150 men be sent? All quiet. The two