page_title: Submarine mines in United States harbor defense
hierarchical_section_title: Submarine mines in United States harbor defense
caption_attribution_description: English: This photo was taken in August, 2010 at Ft. Warren on Georges Island in Boston Harbor. It shows a WW2-era, spherical controlled mine that is on display at the fort. When in use, the mine held 200 lb. of TNT and was anchored to the bottom. This mine is resting on top of its anchor, although when used, it would have floated 20 or more feet above the anchor.The anchor is stamped with the date "1941." The steel loop on top of the mine was used to attach a buoy, which would have floated on the surface, above the mine. The thin steel wire visible here is modern, used to tie the mine to the anchor for exhibition purposes.
context_page_description: The modern era of defending American harbors with controlled mines or submarine mines began in the post-Civil War period, and was a major part of US harbor defenses from circa 1900 to 1947.
context_section_description: The modern era of defending American harbors with controlled mines or submarine mines (originally referred to as "torpedoes") began in the post-Civil War period, and was a major part of US harbor defenses from circa 1900 to 1947.
caption: This WW2-era mine, with its anchor, is on display at Fort Warren in Boston Harbor.
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