HEADQUARTERS, Certain, Va., December 6, 1861.

General S. COOPER, Adjutant and Inspector General.

SIR: I have just received from the Adjutant and Inspector General.

Special Orders., Numbers 252 [of 3rd instant].

This order forms two brigades of Mississippi volunteers "without delay."

I would respectfully bring to the attention of the War Department the following facts, which induce me to request most urgently as suspension of the execution of this order. The carrying it into immediate effect will involve the withdrawal from the field for the spare of five or six days of not less then nine effective regiments. The subtraction of so considerable a force, even for one day, at this crisis, would of itself be attended with extreme peril. Of the nine regiments of Mississippians in this army the Second and the Elewent are in General Whiting's brigade, near Dumfries; the Thirteenth, Seventeenth, Eighteenth, and Twenty-first in General Griffith's, near Leesburg; the Twelfth, Sixteenth, and Nineteenth near Centreville.

The force as now arranged are perfectly familiar with respective position; officers and men have become accustomed to each other, are acquainted with the nature of the ground they occupy, &c. The execution of Orders, Numbers 252, word a complete revolution in the organization of the army, and from this position to Dumfries and Leesburg.

Should the enemy attack us whilst these changes sos statio are in process (an event by no means improbable), it would be almost impossible to avert disaster to our arms. A convention that any sudden change of a material nature in the existing organization of this army will be of serious detriment force me to solicit the continuance of the discretion left me in General, Numbers 15.

The front occupied by this army extends near 50 miles, the enemy being only half that distance, and meditating (according to last information) an immediate attack upon us at all points with immense numerical odds. I respectfully assure the Department that the mischief consequent upon the immediate enforcement of Special Orders, Numbers 252, cannot well be exaggerated.

As General Griffith has already a brigade of four regiments of Mississippi volunteers, I would also suggest that no injury will result from a postponement of the contemplated changes.

Most respectfully, your obedient servant,
J. E. JOHNSTON,

General.

HEADQUARTERS, Centreville, December 6, 1861.

Brigadier-General WHITING:

DEAR GENERAL: I am a little exercised on the subject of our communications. The blocking of the road near Greenwood Church was, I suppose, to cover your left flank. Could it be so done as to give us access to you? Think of it, and tell us how to approach you. I don's want our communications to be interrupted either by Davis' Ford or Bland's. Should we go to you, it might he well to do so two columns. It would be well, therefore, to observe river as your strength will permit-the Occoquan, I mean.