[citation needed] The fort was renamed for the U.S. patriot commander in the Battle of Sullivan's Island, General William Moultrie.

A total of 31 guns commanded the approach from Five Fathom Hole offshore, past the island and the Middle Ground shoal, before ships could enter the harbor.

Royal Navy Admiral Sir Peter Parker led a fleet of nine warships in an attack against the fort—known as Fort Sullivan and incomplete—on June 28, 1776, near the beginning of the American Revolutionary War.

[3] The soft palmetto logs did not crack under bombardment but rather absorbed the shot; cannonballs reportedly even bounced off the walls of the structure.

William Moultrie, commander of the 2nd South Carolina Regiment, and his four hundred men fought a day-long battle that ended with Parker's heavily damaged fleet being driven from the area.

[3] Nevertheless, the Patriots won the war, and British troops departed in 1782, at which time the flag was presented in Charleston, by General Nathanael Greene, commander of the southern Regulars.

[6] Fort Moultrie was rebuilt as part of the Second System of fortifications in 1808–09, under the direction of Army engineer Alexander Macomb.

The Army altered the parapet and modernized the armament, but defense of Charleston centered increasingly around newly created Fort Sumter.

Osceola died of malaria in January 1838; the Army buried his corpse at the front gate of Fort Moultrie and thereafter maintained his grave.

With secession growing more imminent, Gardner had made several requests to Secretary of War John B. Floyd for more troops to garrison and defend the undermanned fortress.

Each time his requests were ignored, as Floyd (who joined the Confederacy) was planning to hand the forts in Charleston Harbor over to the secessionists.

In April 1861, Confederate troops shelled Fort Sumter into submission, and the American Civil War began.

The rifled cannon proved its superiority to brickwork fortifications but not to the endurance of the Confederate artillerymen who continued to man Fort Moultrie.

In February 1865, as General Sherman marched through South Carolina, the Confederate soldiers finally abandoned the rubble of Fort Moultrie and evacuated the city of Charleston.

[9][10] After the US entered World War I, Battery Gadsden's four 6-inch guns were removed for service on field carriages on the Western Front in 1917 and were never returned to the fort.

[9] Following World War I there were several changes at Fort Moultrie as part of a forcewide partial disarmament of the coast defense system.

[17] The Marshall Military Reservation, a sub-post of Fort Moultrie, was established in the northeast part of Sullivan's Island to accommodate the new batteries.

[10] The unnamed battery of four 155 mm M1918 towed guns on concrete Panama mounts was established in 1941 to quickly augment Charleston's harbor defenses.

After the war, due to changes in military technology, including submarines and nuclear weapons, seacoast defense of the United States ceased to be a viable strategy.

The preserved Harbor Entrance Control Post and BCN 520 (now a private residence) are the main relics of the World War II era.