HEADQUARTERS CAVALRY CORPS, December 24, 1863.

Colonel TAYLOR,
Commanding Second Cavalry Division:

The within communication is furnished for your information.

The major-general commanding directs that you have your brigades at Warrenton and Bealeton, keep a sharp lookout, and report at once to these headquarters any information that you may gain.

Very respectfully,

E. B. PARSONS,

Captain, Acting Assistant Adjutant-General.

[Inclosure.]

WASHINGTON, December 24, 1863.

Major-General MEADE:

A woman comes in and reports that one of the rebel cavalry engaged in the last raid was at her house,and said that the affair was a failure, but they were preparing for another on a large scale; that there would be about 5,000 engaged in it. Should this prove true, I have not competent force to prevent it or save the road. She reported that the expedition will start the last of this week.

C. C. AUGUR,

Major-General.

HDQRS. ARMY OF THE POTOMAC, December 24, 1863.

(Received 2 p.m.)

Major General C. C. AUGUR,
Commanding, Washington:

I doubt if the enemy can spare 5,000 cavalry for a raid. I have, however, directed General Crawford to relieve your people at Bull Run bridge and assume the defense of that point. It will be almost impossible to prevent some damage being done by raids in force, but by holding the most important points we can easily repair damage at other places. My cavalry in the rear are directed to be on the alert.

GEO. G. MEADE,

Major-General.

WASHINGTON, December 24, 1863.

Colonel ALEXANDER:

It is reported here that another raid upon the Alexandria and Orange Railroad is to be made the latter part of this week. You will please have every possible precaution taken to make a successful resistance. Where block-house are not completed, have such a disposition of the timber made as will afford protection to parties and stores. Have strong barricades on the roads from the Occoquan, and the roads themselves well patrolled. Let every officer on the line of the railroad know of this, so that precaution can be used. The bloc-house at Bull Run bridge can be used by all for defense now. The one at Devereux Station should also be defensible.

By command of Major-General Augur:

J. H. TAYLOR,

Chief of Staff.