Fort Popham was probably part of the Coast Defenses of the Kennebec command at some point. However, references indicate this command was combined with the Coast Defenses of Portland at some time prior to 1917. During World War I, Forts Popham and Baldwin were garrisoned by about 200 men of the 13th and 29th Coast Artillery companies of the Coast Defenses of Portland. Although Fort Baldwin was disarmed in 1924, the mine facilities at Fort Popham may have remained operational through World War II, during which Fort Baldwin was rearmed with towed artillery.