As an artillery post, Fort Terry was heavily armed as part of the Coast Defenses of Long Island Sound. The Army's forts of this type were garrisoned by the Coast Artillery Corps. By 1914 the fort had 11 gun batteries and facilities to control an underwater minefield. In addition the post was home to an advanced fire control system for both the guns and the minefield. The grounds also had a functional 36" gauge railroad built in 1914. The Porter locomotive was used to haul munitions from bunkers to the artillery batteries.