Run or Creek to General Summer's line, on my left. I think this line necessary, as I learn accidentally that some of the spies of the enemy were inside our lines last night. I would most respectfully suggest that the line from Potomac Creek in your front be, if not already done, established at once and made very perfect to prevent the enemy from getting any further information of our movements. You will pardon my suggestions thus direct to you, as some delay always occurs in communicating through proper channels, and it seems to be most desirable that this should be done at once. One of my staff officers, who is the bearer of this, will ascerting from you where the left of your infantry picket-line will reach Potomac Run, in order that our communication may be perfect.

I am, very respectfully, yours,

D. BUTTERFIELD,

Commanding Fifth Corps, Army of the Potomac.

[21.]

SPECIAL ORDERS,
HDQRS. GRAND RESERVE DIVISION,
ARMY OF THE POTOMAC, Numbers 138.
Stafford Court-House, Va., December 18, 1862.

During my temporary absence Brigadier-General Stahel will take command of the troops stationed between Potomac and Chopawamsic Creeks, and will send his reports to the headquarters Army of the Potomac. Brigadier-General Steinwehr, stationed near Falmouth, will also report directly to the headquarters Army of the Potomac, and will send copies of his reports to Lieutenant-Colonel Meysenburg, assistant adjutant-general, at these headquarters.

F. SIGEL,
Major-General, Commanding.

[21.]

HDQRS. ELEVENTH CORPS, ARMY OF THE POTOMAC,
Stafford Court-House, December 19, 1862.

COMMANDING OFFICER DUMFRIES:

Scouts who came in just now report the enemy's cavalry under Hampton at Brentsville, where they are said to have had a skirmish with our cavalry. One division of the enemy's infantry is reported will reach Brentsville to-day, and information less reliable mentions the whole of Jackson's corps on the march in that direction. Have your scouts well out toward Brentsville, Catllet's Station, and Maple Valley, and patrol the country with the utmost vigilance in that direction. Communicate with General Slocum and learn from him what information he has gained and report the same with your information at once. Send a patrol, on receipt of this, to this place with orders to report here. Communicate with the forces at Wolf Run Shoals by patrols. Please forward all information without delay.

By ordeer of Major-General Sigel:

T. A. MEYSENBURG,

Assistant Adjutant-General.

[21.]

HDQRS. ELEVENTH CORPS, ARMY OF THE POTOMAC,
Stafford Court-House, Va., December 19, 1862.

Colonel CESNOLA,

Commanding Cavalry:

The general commanding directs you to patrol and scout country from Stafford Court-House and Aquia westward toward Elkton, Warrenton