Second Battle of Charleston Harbor The Second Battle of Charleston Harbor , also known as the Siege of Charleston Harbor , Siege of Fort Wagner , or Battle of Morris Island , took place during the American Civil War in the late summer of 1863 between a combined Union Army / Navy force and the Confederate defenses of Charleston , South Carolina . Background . After being repulsed twice trying to take Fort Wagner by storm , Maj . Gen . Quincy Adams Gillmore decided on a less costly approach and began laying siege to the fort . Siege . Innovations & Difficulties . In the days immediately following the second battle of Fort Wagner , Union forces besieged the Confederate works on Morris Island with an array of military novelties . Union gunners made use of a new piece of artillery known as the Requa gun — 25 rifle barrels mounted on a field carriage . While sapper s dug zig - zag trenches toward Fort Wagner a second novelty was used — the calcium floodlight . Bright lights were flashed upon the defenders blinding them enough to decrease accurate return fire while the Union gunners fired safely behind the lights . The Confederate defenders also had advantages . The ground the Union sappers were digging through was shallow sand with a muddy base . The trenching efforts also began to accidentally uncover Union dead from the previous assaults on Fort Wagner . Disease and bad water plagued soldiers on both sides . Garrison . The Union army maintained a constant rotation of soldiers to man the forward trenches of the " grand guard " . During the evening of August 16 a Confederate artillery shell burst through the bombproof serving as the headquarters for Colonel Joshua B . Howell , commanding officer of the grand guard that evening . A shell fragment struck Colonel Howell wounding him severely in the head . Despite Howell ' s quick recovery the incident prompted the Union commander to exclusively use veteran troops in the forward trenches . Confederates also kept a constant rotation of soldiers through Fort Wagner and Battery Gregg . During the night rowboats would bring fresh troops from the mainland to replace the garrison . Even though they had won a substantial victory at Fort Wagner the Confederates fully expected the campaign to continue . Having a large garrison to draw from Gen . P . G . T . Beauregard was prepared to continue the campaign . Immediately in command of Confederate forces surrounding Charleston was former career army officer and South Carolina businessman Roswell S . Ripley . Ripley ' s forces were spread throughout fortifications surrounding Charleston Harbor and included a division of local South Carolina militia . Gilmore and Admiral John A . Dahlgren requested reinforcements from General - in - Chief Henry Halleck . Halleck was reluctant but nevertheless a division from the Army of the Potomac was transferred to the south under George H . Gordon . General John G . Foster , Union commander of the Department of North Carolina , enthusiastically sent a division of reinforcements telling Gilmore " Charleston is too important to be lost when so nearly won " . Batteries . Despite the marshy conditions on Morris Island , Union forces had constructed powerful batteries to combat Fort Wagner . These batteries were often named in honor of fallen leaders such as Batteries Strong , Reynolds , Kearny and Weed . Others were named for high ranking army officers such as Batteries Rosecrans and Meade . Inside Fort Wagner only one 10 - inch Columbiad faced seaward and the few landward guns were in poor condition . During Colonel Lawrence M . Keitt ' s tenure in command of the Confederate garrison he established signal stations on Fort Wagner ' s west wall to coordinate with Confederate batteries on James Island . Keitt ' s replacement , General Johnson Hagood , made better use of sharpshooters and the few landward guns to impede the Union siege works upon the fort . The Confederates protected their own guns and bombproofs but exposed themselves to Union Naval fire and in the end could only slow the Union trenches . Swamp Angel . On August 2 Union engineers began constructing a battery further inland with the intention of bombing the city of Charleston directly . By August 17 the massive battery was ready for its armament . Lieutenant Charles Sellmer with a detachment of the 11th Maine Infantry was called in to man the 200 - pound Parrott rifle now being referred to as the " Swamp Angel " . On August 21 Gilmore sent an ultimatum to Beauregard to abandon Forts Wagner and Sumter or Charleston would be fired upon . When Gilmore received no reply by the following day the first shot was fired from the Swamp Angel into Charleston using the steeple of St . Michael ' s Church for a bearing . On August 22 Confederate batteries tried in vain to silence the Swamp Angel . Beauregard scorned Gilmore for turning his guns on a civilian city and demanded an opportunity to evacuate to citizens . Gilmore complied with a day of cease - fire but also took the opportunity to express the fact that Charleston was a legitimate military target as an ammunition supply . The firing resumed but on the 36th shot the Swamp Angel burst and was not replaced during the campaign . It was the first time a civilian population was deliberately targeted for military purposes during the Civil War . Fort Sumter . Despite trenching difficulties , by mid - August Gillmore had his siege guns within range of Fort Sumter . On August 17 , he opened fire and during the first day of the bombardment nearly 1 , 000 shells were fired . By August 23 , the masonry had been turned to rubble and Beauregard removed as many of the fort ' s guns as possible . Gillmore wired the War Department that " Fort Sumter is a shapeless and harmless mass of ruin " . However , the bombardment of Fort Sumter would continue in general until December 31 , 1863 . Fall of Fort Wagner . Attacks on rifle pits . Gillmore ' s attention returned to Fort Wagner . On September 5 , Gillmore and Admiral Dahlgren attacked with an intense bombing of Fort Wagner for 36 hours killing 100 of the remaining defenders . By now Gillmore ' s forces were close enough to the Confederate works for the infantry to take action . On August 21 Colonel George B . Dandy led the 100th New York Infantry in a rush toward Fort Wagner ' s rifle pit s . The New Yorker ' s quickly established a temporary picket line but their success was short lived . General Hagood ordered a counterattack which drove off Dandy ' s men . Following Dandy ' s attack Confederate engineers began working to strengthen the rifle pits , hoping to force the Union army into mounting another costly assault . Before work could be completed Gilmore ordered division commander General Alfred H . Terry to capture the rifle pits . Terry prepared the 24th Massachusetts Infantry from Brigadier General Thomas G . Stevenson ' s brigade to lead the attack . In support was the 3rd New Hampshire Infantry . Each member of the 24th Massachusetts was equipped with an additional two shovels to immediately rebuild the rifle pits once taken . On the evening of August 25 General Stevenson personally led the attack forward covered by fire from the requa guns . The attack overran the 61st North Carolina Infantry , many of whom surrendered . Colonel George P . Harrison , the fort ' s commander , ordered an artillery counterattack but the rifle pits were already turning into a new siege line . Evacuation . Conditions within the fort were becoming intolerable , and the garrison commander , Colonel Lawrence M . Keitt , informed General Beauregard that he now had only 400 men capable of defending the fort . Therefore on the evening of September 6 – 7 , Beauregard ordered Confederate forces to abandon their positions on Morris Island . On September 7 , Union troops occupied Fort Wagner . Aftermath . Fort Wagner had withstood 60 days of constant bombing and held off a much larger Union army . Yet the Union army and navy had captured an important position at the mouth of Charleston Harbor and reduced its most formidable fortress to rubble . Despite this , the city of Charleston and Fort Sumter itself would remain in Confederate control until William T . Sherman ' s armies marched through South Carolina in 1865 .