Following Beauregard’s bombardment in 1861, Confederate forces occupied Fort Sumter and used it to marshal a defense of Charleston Harbor. Once it was completed and better armed, Fort Sumter allowed the Confederates to create a valuable hole in the Union blockade of the Atlantic seaboard.
The first Union assault on Fort Sumter came in April 1863, when Rear Admiral Samuel Francis Du Pont (1803-1865) attempted a naval attack on Charleston. Commander of the South Atlantic Blockading Squadron, Du Pont arrived in Charleston with a fleet of nine ironclad warships, seven of which were updated versions of the famed USS Monitor.
While Du Pont had hoped to recapture Fort Sumter—by then a symbol of the Confederate rebellion—his attack was poorly coordinated and met with unfavorable weather conditions. In collaboration with Fort Sumter, Confederate batteries commanded by P.G.T. Beauregard hammered the ironclad fleet with artillery fire, and underwater mines posed a constant threat to the ships’ hulls. Outgunned and unable to properly maneuver in heavy currents, Du Pont’s fleet eventually withdrew from the harbor after taking over 500 hits by Confederate guns. Only one Union soldier was killed during the battle, but one of the ironclads, the Keokuk, sank the next day. Five Confederates were killed during the attack, but the damage to Fort Sumter was soon repaired and its defenses improved. Confederate soldiers even managed to salvage one of the Keokuk’s 11-inch Dahlgren guns and mount it on the fortress.
In July 1863 Union troops laid siege to Fort Wagner, a valuable post on Morris Island near the mouth of Charleston Harbor. After being met with heavy fire from Fort Sumter, Union General Quincy Adams Gillmore (1825-1888) turned his guns on the fort and unleashed a devastating seven-day bombardment. On September 8 a force of nearly 400 Union troops attempted to land at Fort Sumter and capture the post by force. Union Rear Admiral John Dahlgren (1809-1870) mistakenly believed the fort was manned by a skeleton crew, but the landing party was met by over 300 Confederate infantry, who easily repulsed the assault.
Following the failed infantry attack, Union forces on Morris Island recommenced their bombing campaign on Fort Sumter. Over the next 15 months, Union artillery effectively leveled Fort Sumter, eventually firing nearly 50,000 projectiles at the fort between September 1863 and February 1865. Despite suffering over 300 casualties from the Union bombardments, the beleaguered Confederate garrison managed to retain control of the fort until February 1865. Only when Union General William T. Sherman was poised to capture Charleston did the Confederates finally evacuate. Union forces would reclaim Fort Sumter on February 22, 1865. Robert A. Anderson and Abner Doubleday, the two commanding officers from the original siege of Fort Sumter, would both return to the fortress on April 14, 1865, for a flag raising ceremony.