In a previous dispatch I informed you of my anticipation of the fall of Fort Donelson. These movements were commenced under that impression. The enemy attacked the fort on the 13th instant at sunrise in great force wit gunboats and by troops on land. The assault was continued with vigor and the enemy repulsed with loss.

On the morning of the 15th our forces, under the command of General Floyd, about 10,000 strong, advanced from their trenches upon the enemy, more than double their number, and drove him back about 2 miles, capturing his artillery, taking prisoners, and forcing his positions. The conflict was one of the most sanguinary of the war, and continued from dawn until night-fall, with a loss of about 1,000 killed and wounded on our part.

During the night the enemy was heavily re-enforced by thirteen transports coming to his relief loaded with fresh troops, while our men were exhausted by cold, privation, and three days' continued battle.

During the night, the position being found no longer tenable in consequence of the exhaustion of the men, and the enemy having obtained a lodgment on the extreme right in the entrenchments, the fort being uninjured, General Floyd and a portion of his command withdrew and General Pillow retired, leaving General Buckner in command of the place and the remaining troops.

General Buckner informed me that 4 o'clock on the morning of the 16th he had a flag of truce, which I presume was for the purpose of surrendering, though I have not received official information of the fact.

I have the honor to remain, your obedient servant,

A. S. JOHNSTON,

General, C. S. Army.

Honorable J. P. BENJAMIN,

Secretary of War, Richmond, Va.

P. S.- General Floyd mentions the fact that the loss of the enemy, killed and wounded, was much greater than our own - at least 1,500.

Numbers 2. Report of Brigadier General O. M. Mitchel, U. S. Army.

HDQRS. THIRD DIVISION, DEPARTMENT OF THE OHIO,
Bowling Green, Ky., February 15, 1862.

GENERAL: I have the honor to announce that the advance guard, consisting of Colonel Turchin's brigade, under cover of artillery from each of the batteries, commanded by Captain Loomis, effected a passage of the river during the night by means of a large flat-boat, which was found by our scouts during the afternoon at a large flouring-mill about 4 miles below the town of Bowling Green. The advance guard, accompanied by a detachment of Colonel Kennett's cavalry, supported by three regiments of a reserve from the main body, marched upon the town, and entered without finding an enemy at 5 o'clock this morning. Our cavalry pickets are now thrown forward 5 or 6 miles along the railroad leading to nashville, the railroad leading to Russellville, and the turnpike leading to Nashville. Every precaution has been taken to prevent the surprise of our advance guard. The entire division is encamped upon the north side of the river near the railroad, and convenient to wood and