HEADQUARTERS FORT SUMTER, September 12, 1863.

CAPTAIN: I have the honor to submit a report of the late action at this post.

On the 4th instant, pursuant to Special Orders, Numbers 298. headquarters First Military District, Department of South Carolina, Georgia, and Florida, I assumed command, with the Charleston Battalion of Infantry (commanded by Major J. A. Blake) as a garrison. All the available guns having been already dismounted,a the defense was to be conducted by infantry.

The condition of the work was as follows. The gorge A had been so cut by the enemy's artillery that the scarp had assumed the form of an inclined place with a dip of about 45o. The wall of the east face had been shot away, leaving the arches (which had been filled with sand) exposed. The northeast face was comparatively secure. The northwest contained several serious breaches, and one of very considerable size, B. This was defended by a barricade. The others were securely obstructed. The west face was uninjured, the lower tier of embrasures being merely closed by their usual shouters. The main sally-port in this face had been pierced for musketry, and commanded the wharf.

Dispositions similar to the following were habitually made: Captain [J. W.] Hopkins' company (D), 43 men, lay on their arms on the parapet of the gorge and Captain [F. T.] Miles' company (E), the sentinels on post, were to defend the sally-port. Captain [T. Y.] Simons' company (B), 28 men, lay at the entrance on the west face. In case of an alarm, Captain [S.] Lord's company (F), 42 men, was to occupy the southwest angle and support Captain Hopkins on the right. lieutenant [J. C.] Saltus' company (A), 12 men, at the southeast, was to support him on the left. Lieutenant[J. G.] Harris' company (G), 25 men, was to occupy the northeast angle. Captain [J. M.] Mulvaney, Company C, 43 men, was to support Captain Miles. IN case their services should not be needed, the last four companies were to remain formed on the parade below their respective positions, as as to ready to move to any weak point.

I had procured from Charleston a supply of hand-grenades and fireballs. Detachments of men for each of these kinds of service were kept constantly in position at three different points of the parapet.

I requested Captain Champneys, the engineers in charge, to plant two fougasses in the wharf leading from the gorge. During the attack he kindly superintended their delivery.

At 1 a. m., while observing a monitor which had taken a position near the fort, I saw the enemy pulling up from the eastward in two columns, the head of the one directed upon the northeast, that of the other upon the southeast, angle of the fort. I ordered up three companies within supporting distance, and reserved our fire until they had deployed and commenced to land. The outer boats replied rapidly for a few minutes.

The crews of those that had effected a landing sought refuge from the galling fire under the projecting masses of the wall, whence grenades and fire-balls soon dislodged them.

The fire of the Chicora, lying at a short distance sought refuge from the galling fire under the projecting masses of the wall, whence grenades and fire-balls soon dislodged them.

The fire of the Chicora, lying at a short distance to the northward; of Sullivan's Island, to the northeast, and of Fort Jonson, to the westward, encircled the work and effectually assisted to prevent any re-enforcement coming up.