HEADQUARTERS FOURTH ARMY CORPS, MEDICAL DIRECTOR'S OFFICE, Huntsville, Ala., January -, 1865.

SIR: I have the honor to submit the following report of the operations of the medical department of this corps during the battles of December 15 and 16 near Nashville, Tenn.:

On the morning of December 14 orders were received ot be ready at 6 a. m. December 15 to move upon the enemy's position. The hospitals of this corps, which, since the 2nd of the month, had been located near the city on the Franklin pike, were ordered to be broken up and the hospital train to be parked on the Hill borough pike, there to remain until further developments; the sick were transferred to general hospital. At 7 a. m. December 15 the troops of this corps moved out by the Hillsbourough pike in front of the line of works occupied by them during the two weeks previous, and formed as follows: First Division on the right, connecting with the left of Major General A. J. Smith's command; Second Division on the left of the First; and the Third Division on the left of the Second and somewhat retired. The hospitals of the corps were at once established directly on the Hillsborough pike, and about a quarter of a mile in rear of the line of works. The site selected was the lawn in front of a large brick house; water was abundant and good. Detachment form each division ambulance train were close in rear of the troops; the remaining ambulances were parked in rear of the works and ready to move out when required; the stretcher men were with their respective regiments. During the fighting of the 15th ultimo the line of this corps was advanced nearly two miles. The loss in wounded was not severe, being only 203 men. The wounded were promptly removed the field and cared for at division hospitals. After dark, the fighting having ceased and all operations and dressing having been attended to, the wounded were transferred to general hospital. As the position of the corps had now changed from the Hillsborough pike to the Franklin pike, the hospital trains was ordered to be loaded and ready to move at daylight on the 16th ultimo.

On the morning of the 16th ultimo the position of the troops of this corps was as follows: The Third Division on the left of the Franklin pike, connecting with the right of Major-General Steedman's command; Second Division in center; and the First Division on the right, connecting with the command of Major General A. J. Smith. The hospitals were located on the right and left of the Franklin pike at "The Springs," about two miles in advance of the old line of works; the ambulances were near the troops. The fighting of to-day was much more severe than that of yesterday, although the casualties were wonderfully slight. Four hundred and ninety-five men of this corps were wounded and taken to hospital. Shell wounds were of more frequent occurrence than on the previous day. At night the wounded, after being attended to, were ordered to be transferred to general hospital and the hospital trains to be leaded and ready to move at early day, either for the establishment of the hospitals near the troops in the event of another battle, or to be ready to follow the corps in case, as was probable, the enemy should retreat.

The medical and ambulance officers of the corps deserve great praise for the faithful and efficient manner in which they performed their arduous duties. With little or no rest for fifty hours, they yet cheerfully and fearlessly continued at their posts. I can truly say that I have never seen wounded more promptly removed from the field or better carried for in division hospitals.