HEADQUARTERS CAVALRY CORPS, December 22, 1863.

Five prisoners have just been brought in by General Elliott's troops, representing Armstrong's, Morgan's, and Martin's divisions. They say the the enemy has two corps of cavalry, 10,000 in all; that Longstreet has been re-enforced from Virginia, and has 40,000 men. McKinney's Ford is still 2 feet higher than when crossed by General Elliott's brigade.

S. D. STURGIS,
Brigadier-General.

Major-General FOSTER.

HEADQUARTERS CAVALRY CORPS,
Near Strawberry Plains, Tennessee, December 22, 1863. (Received 23d.)

GENERAL: General Elliott will cross his remaining brigade over the Holston early to-morrow, and I have ordered Colonel Wolford to cross his division at McKinney's Ford at daylight. Colonel Garrard will cross his brigade at the same time and place.

I have requested Major-General Parke to order a demonstration on his front by means of the brigade of Colonel Foster's division, now (temporarily) under his control. You will perceive I leave two brigades behind-the one just referred to,of Colonel Foster's division, and the one sent from Colonel Wolford's division to the vicinity of Tazewell.

In view of the sudden rise the Holston and French Broad Rivers are subject to at this season, I would respectfully urge upon the general commanding the great importance of a pontoon bridge at Strawberry Plains, in order to keep open our line of retreat; for should these rivers suddenly, and Longstreet be able by the railroad to throw a column of infantry against us, our safety might be placed in great jeopardy in the absence of such a bridge. Of his power to use the railroad in any event I know nothing; of this the commanding general is probably better posted than myself.

I am, general, very respectfully, your obedient servant,

S. D. STURGIS,

Brigadier-General, Commanding Cavalry Corps.

Brig. General E. E. POTTER,

Chief of Staff.

No. 41.

Reports of Brig. General William P. Sanders, U. S. Army, commanding First Cavalry Division.

HEADQUARTERS FIRST DIVISION CAVALRY CORPS, November 14, 1863.

GENERAL: Major Graham was attacked early this morning at Maryville; he had two companies as scouts. The rebels rode into his camp, and he reports that most of his men are captured. I hope a number of them will get in. I moved out with two regiments,