HEADQUARTERS DEPARTMENT OF THE SOUTH,
Hilton Head, S. C., January 17, 1865.

GENERAL: The military changes since the date of my last report embrace the removal of the Seventeenth Corps of General Howard's wing of General Sherman's Army, from Savannah to Beaufort, and their advance; also the removal of the Fifteenth Corps of the same wing, to the same place.

On the night of the 13th General Howard threw a brigade of the Seventeenth Corps (General Blair) across Port Royal Ferry, and constructed a pontoon bridge. On the 14th he advanced with the whole corps, the leading division reaching the works at Pocotaligo that night. During the night the enemy retreated from all their works in front of Generals Blair and Hatch.

\On the morning of the 15th General Blair moved forward and occupied the railroad. General Hatch also moved forward and occupied the railroad in his front and also works at Tullifinny, Coosawhatchie, Dunson's Bluff, and Bee's Creek. A portion of the force was at once employed in destroying the Charleston and Savannah Railroad. The enemy's infantry retreated on the railroad toward Charleston, the Artillery and cavalry toward Branchville. It is reported that they intend to make an attempt to check General Sherman's advance near the Ashepoo River at a place called Green Pond. It is still further reported that the enemy intend to make a determined stand at Branchville, and, if possible, to hold Charleston. It is possible that the intention of the enemy is to evacuate Charleston. The belief that this will be the case is founded on information obtained from deserters, escaped Union officers, and refugees. They report the following facts:

First. Very Little wok is being done upon the defenses in the rear of the city.

Second. That they have moved all of [their] light guns from Charlesto.

Third. All the machinery in the arsenal and Government chops has been removed to Charlotte, M. C.

Fourth. Before removed from the shops the last piece work done was to make 400 spikes for spiking cannon and issuing the same to the officers who were to use them.

Fifth. All the negroes, except one to each officer and citizen, have been ordered to be removed from the city.

Sixth. The citizens. including women and children, are allowed to remain.

These points almost convince me that it is altogether probable, if not conclusive, that they intend to evacuate Charleston. A determined stand will undoubtedly be made at Branchville. General Sherman, however, will make quick work with any force that they may have there. The reports represent that the whole force in South Carolina consists of General Hardee's force, or at least the portion that remained after a part of the Georgia militia went home, amounting to about 10,000 men, regulars and militia. In addition, there are about 2,000 men in and around Charleston. The First Division of Longstreet's corps, 3. 000 strong, is reported to be here; also Hagood's (South Carolina) brigade, 1. 100 strong and Wheeler's cavalry, 4. 000 strong, making a total of 20. 100.

Considerable activity is apparent at the sea-board batteries of Charleston This may work to strengthen the batteries, a removal of the guns, or a ruse to cover the evacuation. General Sherman is rapidly preparing to move forward and will soon be in full motion, the advance corps having already started.