(A different type of device is also sometimes referred to as a "magnetic mine". The Limpet Mine is "magnetic" in the sense that it has a hefty magnet that lets an operator attach it personally to the hull of a ship, to be detonated when he is at a safe distance. These are not considered here.)

The original Mark I Magnetic Mine ('Type GA') This was the first model dropped in coastal waters by the Germans early in World War II. This is the actual device that landed on the mud flats in the Thames Estuary in November 1939, and provided the clues needed to develop countermeasures. [Also seen in the 1970's BBC programme "The Secret War".] It is now on display in HMS Belfast on the South Bank of the Thames. (Belfast herself was damaged by a magnetic mine that same November.) You can see a photo of it as it lay on the mud flats in 1939, together with a picture of Lt Cdr John Ouvry and his crew — who actually did the hazardous job of defusing it — on HMS Vernon's own History pages.



November 2009 marked the 70th anniversary of the events described above, and you may be interested in an expanded account (pointed out to me by a reader) of the situation in late 1939, and the Royal Navy's role at the time, that was posted at that time here.