SIR: I have the honor to submit the following detailed report of the bombardment and surrender of Fort Sumter and the incidents connected therewith:

Having completed my channel defenses and batteries in the harbor necessary for the reduction of Fort Sumter, I dispatched two of my aides at 2.20 p.m., on Thursday, the 11th of April, with a communication to Major Anderson, in command of the fortification, demanding its evacuation. I offered to transport himself and command to any port in the United States he might elect, to allow him to move out of the fort with company arms and property and all private property, and to salute his flag in lowering it. He refused to accede to the demand. As my aides were about leaving Major Anderson remarked that if we did not batter him to pieces he would be starved out in a few days, or words to that effect. This being reported to me by my aides on their return with his refusal, at 5.10 p.m., I deemed it proper to telegraph the purport of his remark to the Secretary of War. In reply I received by telegraph the following instructions at 9.10 p.m.: “Do not desire needlessly to bombard Fort Sumter. If Major Anderson will state the time at which, as indicated by him, he will evacuate, and agree that in the mean time he will not use his guns against us unless ours should be employed against Fort Sumter, you are authorized thus to avoid effusion of blood. If this, or its equivalent, be refused, reduce the fort as your judgment decides to be most practicable.”

At 11 p.m. I sent my aides with a communication to Major Anderson based on the foregoing instructions. It was placed in his hands at 12.45 a.m. 12th instant. He expressed his willingness to evacuate the fort on Monday at noon if provided with the necessary means of transportation, and if he should not receive contradictory instructions from his Government or additional supplies, but he declined to agree not to open his guns upon us in the event of any hostile demonstrations on our part against his flag. This reply, which was opened and shown to my aides, plainly indicated that if instructions should be received contrary to his purpose to evacuate, or if he should receive his supplies, or if the Confederate troops should fire on hostile troops of the United States, or upon transports bearing the United States flag, containing men, munitions, and supplies designed for hostile operations against us, he would still feel himself bound to fire upon us, and to hold possession of the fort.

As, in consequence of a communication from the President of the United States to the governor of South Carolina, we were in momentary expectation of an attempt to re-enforce Fort Sumter, or of a descent upon our coast to that end from the United States fleet then lying at the entrance of the harbor, it was manifestly an imperative necessity to reduce the fort as speedily as possible, and not to wait until the ships and the fort should unite in a combined attack upon us. Accordingly my aides, carrying out my instructions, promptly refused to accede to the terms proposed by Major Anderson, and notified him in writing that our batteries would open upon Fort Sumter in one hour. This notification was given at 3.20 a.m. of Friday, the 12th instant. The signal shell was fired from Fort Johnson at 4.30 a.m. At about 5 o'clock the fire from our batteries became general. Fort Sumter did not open fire until 7 o'clock, when it commenced with a vigorous fire upon the Cummings Point iron battery. The enemy next directed his fire upon the enfilade battery on Sullivan's Island, constructed to sweep the parapet of Fort Sumter, to prevent the working of the barbette guns and to dismount them. This was also the aim of the floating battery, the Dahlgren battery, and the gun batteries at Cummings Point.

The enemy next opened on Fort Moultrie, between which and Fort Sumter a steady and almost constant fire was kept up throughout the day. These three points - Fort Moultrie, Cummings Point, and the end of Sullivan's Island, where the floating battery, Dahlgren battery, and the enfilade battery were placed - were the points to which the enemy seemed almost to confine his attention, although he fired a number of shots at Captain Butler's mortar battery, situated to the east of Fort Moultrie, and a few at Captain James' mortar batteries at Fort Johnson.

During the day (12th instant)the fire of my batteries was kept up most spiritedly, the guns and mortars being worked in the coolest manner, preserving the prescribed intervals of firing. Towards evening it became evident that our fire was very effective, as the enemy was driven from his barbette gun which he attempted to work in the morning, and his fire was confined to his casemated guns, but in a less active manner than in the morning, and it was observed that several of his guns en barbette were disabled. During the whole of Friday night our mortar batteries continued to throw shells, but, in obedience to orders, at longer intervals. The night was rainy and dark, and as it was almost confidently expected that the United States fleet would attempt to laud troops Upon the islands or to throw men into Fort Sumter by means of boats, the greatest vigilance was observed at all our channel batteries, and by our troops on both Morris and Sullivan's Islands.

Early on Saturday morning all of our batteries reopened upon Fort Sumter, which responded vigorously for a time, directing its fire specially against Fort Moultrie. About 8 o'clock a.m. smoke was seen issuing from the quarters of Fort Sumter. Upon this the fire of our batteries was increased, as a matter of course, for the purpose of bringing the enemy to terms as speedily as possibly, inasmuch as his flag was still floating defiantly above him. Fort Sumter continued to fire from time to time, but at long and irregular intervals, amid the dense smoke, flying shot, and bursting shells. Our brave troops, carried away by their natural generous impulses, mounted the different batteries, and at every discharge from the fort cheered the garrison for its pluck and gallantry, and hooted the fleet lying inactive just outside the bar.

About 1.30 p.m., it being reported to me that the flag was down (it afterwards appeared that the flag-staff had been shot away), and the conflagation from the large volume of smoke being apparently on the increase, I sent three of my aides with a message to Major Anderson to the effect that seeing his flag no longer flying, his quarters in flames, and supposing him to be in distress, I desired to offer him any assistance he might stand in need of. Before my aides reached the fort the United States flag was displayed on the parapet, but remained there only a short time, when it was hauled down and a white flag substituted in its place. When the United States flag first disappeared the firing from our batteries almost entirely ceased, but reopened with increased vigor when it reappeared on the parapet, and was continued until the white flag was raised, when it ceased entirely. Upon the arrival of my aides at Fort Sumter they delivered their message to Major Anderson, who replied that he thanked me for my offer, but desired no assistance.