On April 7th, Flag Officer Samuel F. DuPont's fleet steamed into Charleston harbor to attack Fort Sumter. Among the fleet's 9 ironclads were the frigate New Ironsides, 7 moniters, and Keokuk, a small ironclad of an untried design. During the course of the fight, the Confederate guns in Fort Sumter and Fort Moultrie fired a total of 2,209 times and scored a large number of hits, chiefly on the moniters and Koekuk, which becuase of their shallow drafts, were able to approach more closely. Some of these vessels were temporarily disabled. The Keokuk wallowed lowere and lower in the Atlantic swells until it sank the next morning. The fleet was not able to generate much firepower in response to the Confederate bombardment it recieved. New Ironsides, because of its deep draft, had to remain at long range. Keokuk and the moniters mounted 2 guns each, which had slow rates of fire in the constricted space of the moniter's revolving turrents, and Keokuk's small casemates. During the entire fight, the ironclads got off a combined total of only 154 shots. These did minimal damage to the walls of Fort Sumter, which was soon repaired. Clearly, even the most powerful ironclads available in 1863 were not going to be able to pound the Charleston defenses into submission by themselves. Lincoln ordered DuPont to maintain his position inside of Charleston harbor, but that was all DuPont could do.
Thus, matters stood until July, when Sec. of the Navy Gideon Welles, displeased with DuPont for the failure of the attack, replaced him with Rear Adm. John A. Dahlgren with the understanding that Dahlgren would push operations against Charleston more aggresively than before. For these new operations, Dahlgren was to have the active cooperation of army forces, under Maj. Gen. Quincy A. Gillmore. On July 10th, Gillmore's troops landed on the southern end of Morris Island, which lay to the south of Charleston Harbor, under cover of heavy naval bombardment that turned into another fierce battle between ships and shore. Gillmore's plan was to advance up the island and take Battery Wagner, a sturdy, sand-and-palmetto-log fortification at the north end of the island. Wagner was an important part of the Charleston defenses, and from its position, Union batteries could bombard Fort Sumter at relatively close range. Moving quickly, Gillmore assaulted Battery Wagner the next day. Advancing with great determination, Union troops pressed forward all the way to the top of Wagner's parapet but could bo no further and soon had to fall back under deadly Confederate fire.
One week later on the 18th, after steady bombardment by the guns of the Union fleet and some 36 pieces of artillery on Morris Island, the Federals charged again, but once again the attack was a bloody failure. Among the several Union regiments that suffered heavy casualties in the assault was the 54th Massachusetts Colored Infantry, whose colonel, the abolitionist Robert Gould Shaw, was among the killed.
Thereafter, Gillmore and his troops settled down for a lengthy seige. Over the weeks that followed, Union naval guns continued to pound Fort Sumter and Battery Wagner while the Union soldiers planted batteries of heavy guns on land and dug their approach trenches cloer and closer to Battery Wagner.
They brought in a massive 200-lb Parrot gun, nicknamed the Swamp Angel, as well as additiona pieces of artillery. By August 11th, the new Union batteries were ready and begun practice bombardments, lofting their shells over Battery Wagner and slamming them against the brick walls of Fort Sumter. The "practice" firing continued for 5 days. Masses of brickwork crumbled on Fort Sumter, but the Confederate garrison worked hard, shoring up their defenses with sand-filled gabions.
Then on the 17th, Gillmore's and Dahlgren's guns unleashed the 1st great bombardment of Fort Sumter, which continued through the firing of 5,009 artillery rounds over the course of the next week. The rain of heavy shells reduced the fort's brick walls to shapeless heaps of sand and rubble, but these, it turned out, were better protection against incoming fire than the brick walls had been. Fort Sumter was reduced to 4 servicable guns, but it still held out. The Swamp Angel, on the other hand, burst on the firing of its 36th round. The Confederates attempted to strike back by sending a small steam torpedo boat to attack New Ironsides, but the effort proved unsuccessful. On the night of September 6-7th, Confederate troops evacuated Battery Wagner and nearby Battery Gregg. The Federals occupied both on the morning of the 7th, but Fort Sumter, now a pile of rubble, still seemed as far from surrendering as ever.