Fort Moultrie is the only area of the National Park System where the entire 171-year history of American seacoast defense (1776–1947) can be traced. Originally called Fort Sullivan.

It was 1775 when American Colonel Moultrie took possession of a fort on Sullivan Island in South Carolina, and he needed a flag. His troops’ clothing was blue. They had silver crescents on their caps, and the words “Liberty or Death.” So a blue flag was sewn, with a crescent in the upper corner. In Moultrie’s words, “This was the first American flag displayed in the South.” The next year, 1776, the Americans were defending Fort Sullivan in a battle with the British.  The blue flag was flying, but during the fight it fell down onto the beach, outside the fort.  Sergeant William Jasper leaped over the parapet, ran the length of the fort and recovered the flag.  He managed to get back into the fort and get the flag fastened and flying again. The Americans fought off the British, and saved the fort. Fort Sullivan was later renamed Moultrie, in honor of Colonel Moultrie’s stand against the British.

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