Magnetic mine and airmining shock in World War II
In November 1939 a Shoeburyness sentry spotted a German Heinkel 105 releasing a magnetic mine into the Thames estuary. British experts recovered the mine and developed the degaussing girdle to counter the threat. The RAF and Fleet Air Arm then dropped parachute mines using Hampden bombers, Lancasters, and Wellingtons, with RAF Polish Squadron crews aiding in mine-laying missions across western Europe.