Built between 1905 and 1912 and named for Jeduthan Baldwin, an engineer for the Colonial army during the Revolutionary War, Fort Baldwin originally consisted of three batteries (Cogan, Hardman, and Hawley). Battery Cogan had two three-inch guns, Battery Hardman had one six-inch disappearing gun, and Battery Hawley had two six-inch pedestal guns. All of these guns were removed in July 1924. During the First World War, Forts Baldwin and Popham held a garrison of two hundred soldiers including the 13th and 29th Coast Artillery. During the Second World War, D Battery, 8th Coast Artillery manned the fort from 1941 to 1943.