The Harbor Mine or Torpedo Complex was constructed during the period of 1908 to 1911 as part of a comprehensive harbor defense system for Narragansett Bay. The two-story concrete structure served as a Mine Storage Warehouse in which the parts required for the assembly of the mines (or torpedoes as they were also called) were stored. This building and the two adjacent one-story structures were equipped with overhead rail cranes capable of lifting and moving heavy parts and subassemblies to tram carts that would transport these components along a narrow-gauge rail system for assembly, insertion of explosives and testing in the nearby buildings before they could be anchored in the waters of the bay.

The second structure, a one-story Cable Tank Building, contained four oblong water tanks made of concrete in which reels of insulated submarine cables were immersed and preserved until needed. These cables eventually connected the mines to a small onshore facility, called a Mine Casemate (one is located the the rear of the warehouse), from where the mines in the waters of the Bay could be detonated. Each of the four tanks could hold 20,000 feet of reeled cable.

All necessary components and cables were moved to the Loading Room, the one-story building at the western end of the Mine Complex, where the mines (torpedoes) were assembled and tested following the addition of the required explosive charges. To facilitate this operation, the overhead crane lowered the mines into circular pits in the floor, allowing mechanics to prepare the mines for movement to the pier via narrow-gauge rail carts, and from there to designated areas of the bay by an Army Mine Planter. Clusters of 19 mines were then lowered into the bay and connected to a land-based mine casemate from where specific groupings could be detonated on command.

Marker can be reached from Fort Wetherill Road.

Courtesy hmdb.org

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