A disappearing gun, added to the Fort Williams battlements before World War I, is pictured manned by National Guard members stationed at the fort in Cape Elizabeth to protect the country's coast lines before, during and after America's official involvement in World War I.

The four men pictured on the left do not appear to be in uniform, and it is likely they are members of the Coast Artillery Corps, who were recruited for weapon and machinery installation. The man pictured on the right may be overseeing the work, due to his being in uniform and carrying a clipboard.