cavalry attached to this corps will occupy Manassas Junction and Brentsville, with strong pickets at Centerville, Bull Run Bridge, and Chantilly. It is desirable, and almost necessary,that in case Centreville should be held as an advance post of Washington, one brigade of infantry should be sent there besides the brigade now under command of Colonel D'Utassy, which he will need to occupy Fairfax Court-House and Fairfax Station, and the line from Bull Run Bridge by Union Mills to Wolf Run Shoals. If Centreville can be given up, which i do not decide, two regiments of infantry should be sent to Fairfax Court-House, or Fairfax Station, to allow Colonel D'Utassy to keep his troops more concentrated. No news of importance has been received from our lines beyond Centreville and Chantilly. Patrols sent to Aldie and Leesburg have seen nothing of the enemy.

F. SIGEL,

Major-General.

HAGERSTOWN, MD., December 11, 1862-10 p.m.

General CULLUM,

Chief of Staff:

All of Slocum's corps, including Gordon's brigade, are gone. I have sent General Kenly, with two regiments, to Harper's Ferry, keeping the other two to look after this part of my line, which will be entirely uncovered if they go.

GEO. W. MORELL,

Major-General, Commanding.

HARPER'S FERRY, W. VA., December 11, 1862.

Major General H. W. HALLECK,

General-in-Chief:

My command has left this place, by order of General Burnside. General Morell telegraphs from Hagerstown that the cavalry of the enemy are at Martinsburg, and that Hill is marching up the valley. This place is not sufficiently protected. Only one regiment of infantry (Fifth Maryland) remains to protect the permanent batteries and property.

H. W. SLOCUM,

Major-General, Commanding.

WAR DEPARTMENT,

Washington, December 11, 1862.

Brigadier-General KELLEY,

Cumberland, Md.:

It is reported that the enemy's cavalry and a part of Hill's corps are advancing on Martinsburg. You will take immediate measures to oppose any movement made by the enemy.

H. W. HALLECK,

General-in-Chief.

HEADQUARTERS ARMY OF THE POTOMAC, December 12, 1862.

Major-General SIGEL:

Our forces are crossing the river, and thus far without opposition. The general commanding desires that you move your command on as rapidly as possible.

JNumbers G. PARKE,
Chief of Staff.