This gave Gillmore complete control of Morris Island clear to Cummings's Point, and as he believed, made him master of Charleston harbor. In that belief he sent a fleet of whaleboats packed with infantrymen to take possession of Fort Sumter. But the Confederates there resisted with a vigor which destroyed most of the boats, disabling their crews, and resulted in the killing or capturing of the infantrymen who constituted their ship's companies. It had been the hope of General Gillmore that when he should thus secure command of the entrance to Charleston harbor the fleet lying outside would press in and complete his work by capturing the city. But in this hope he was disappointed. Admiral Dahlgren, who commanded the fleet, knew far better than Gillmore did the reserve resisting power of the Confederate batteries within the harbor, and he wisely declined to push his vessels into a bay which, if he had resolutely invaded it, would have become quickly a naval graveyard. During all this time it had been Gillmore's ambition to bombard the city of Charleston itself. To that end in August he had brought up to Morris Island an eight-inch rifle gun of exceedingly long range and ordered it planted at a point selected by himself. The point was one so marshy that for a time no platform could be constructed that would support the gun. It is humorously related that the officer constructing it, having been told to make requisitions for whatever materials he might need, formally sent in a requisition for "a hundred men eighteen feet high." At last, however, by driving piles a platform was made and the gun, which the men named the Swamp Angel, was got into position. It threw thirty-six shells into the city of Charleston five miles away, and then burst. In order to reach so great a distance it had been elevated to about 23 degrees. No gun that was ever constructed other than a mortar, can long endure firing at so great an elevation. After his capture of Fort Wagner and Battery Gregg Gillmore resumed his bombardment of the city from the latter point, which lies a mile or two nearer than did the position of the Swamp Angel. Gillmore had succeeded in capturing what had been supposed to be the main defenses to the harbor and the city. He had utterly failed to capture the city itself, or in any way to break the resistance which, to the end, continued to hold the harbor secure against Federal attack. During all this time the Federals had been holding Port Royal and the islands along the coast between Charleston and Savannah. With strong forces they had made many advances inland, hoping to break the railroad line between the two cities and to push through the open country into the rear of one or the other.