Located on Charleston harbor, Fort Johnson was constructed on the northeast point of James Island in 1708. Named after the colony’s proprietary governor Nathaniel Johnson, it was apparently built in response to the 1706 French and Spanish attack on Charleston. The original fortification was replaced by a new work in 1759, which was garrisoned under British authority during the colonial period. During the Stamp Act crisis of 1765, Fort Johnson briefly housed revenue stamps and provided protection to British stamp officials. It was occupied by South Carolina troops under the command of Isaac Motte in 1775 and remained in American hands until 1780, when advancing British troops found it destroyed. A third fort was built in 1793, but this was temporally abandoned after a storm breached its sea wall in 1800. Although the fort was frequently reported to be in dilapidated condition, a brick magazine and Martello tower were constructed between 1800 and 1833. The signal shot that commenced the bombardment of Fort Sumter and the beginning of the Civil War was fired from a Fort Johnson mortar battery on April 12, 1861. An amphibious attack conducted on July 3, 1864, by Federal troops stationed on Morris Island was repulsed by the Confederate garrison. On February 17, 1865, Fort Johnson was abandoned during the Confederate evacuation of Charleston. No military construction is documented after 1865. By 1890 the site was an established maritime quarantine station. In 1972 the majority of the Fort Johnson site was dedicated as a marine resources research center under control of the South Carolina Department of Natural Resources.
Mustard, Harry S. “On the Building of Fort Johnson.” South Carolina Historical Magazine 64 (July 1963): 129–35.
Wilcox, Arthur M., and Warren Ripley. The Civil War at Charleston. Charleston, S.C.: News and Courier, 1966.