Battery Thomson, constructed 1906-1909 by Captain G.P. Howell, is one of a series of batteries extending from Fort Moultrie on the west to the eastern end of Sullivan’s Island. Charleston Harbor has always had some form of fixed harbor defense beginning with Fort Johnson in 1708 and culminating with the construction of these batteries in the fortification of Sullivan’s Island at the mouth of Charleston Harbor. This two, 10 inch gun, coastal defense battery was established in order to command the entrance to the Charleston harbor jetties. It was constructed following the recommendations of the Endicott Board under the Cleveland Administration. The battery, approximately 326 feet long and 84 feet wide, consists of two sections: The glacis and the armament complex. The glacis, a relatively smooth, slightly sloping area on the sides and front of the battery, protects the armament complex from bombardment. The armament complex consists of two recessed disappearing gun platforms, the loading platforms, ammunition hoists (one per gun), and observation post and various staircases and ramps for access. The ocean side of the battery is approximately 10 feet high. Walls and ceilings are of concrete. All machinery and guns were removed in 1947 at the decommissioning of the battery. Listed in the National Register June 25, 1974.