Fort Trenholm is located in South Carolina

Fort Trenholm, also known as Battery Trenholm, is a historic artillery battery located at Johns Island, Charleston, South Carolina. It was built in 1864, to reinforce Fort Pringle and protect the Stono River and Johns Island. It has emplacements for 17 guns. The three-sided earthen redoubt measures approximately 870 feet on its eastern face, 780 feet long on its southern face, and 885 feet long on its western face. It has a 15 foot high parapet wall.^[3]

• http://en.wikipedia.org/wiki/Fort Trenholm