
Larger type of the early German magnetic mine, recovered in 1939, with rule alongside to show its size. © IWM A 30292.

King George VI inspecting Ouvry’s mine at HMS VERNON on 19 December 1939. Found at https://www.vernon-monument.org.uk/history by courtesy of Rob Hoole.
Notes [1] Nick Hewitt, Coastal Convoys, 1939-1945: The Indestructible Highway (Barnsley: Pen & Sword Maritime, 2019), 34-39. [2] Paul Lund and Harry Ludlam, Trawlers Go to War (London: New English Library Ltd. 1974), 10. [3] Commander David Bruhn USN (Ret.) and Lieutenant Commander Rob Hoole RN., Enemy Waters: Royal Navy, Royal Canadian Navy, Royal Norwegian Navy, U.S. Navy and Other Allied Mine Forces Battling the Germans and Italians in World War II (Maryland: Heritage Books, 2019), 37-48. [4] Julian Paul Foynes, The Battle of the East Coast (1939-1945) (Middlesex: J. P. Foynes, 1994), 1-34. [5] David C. Isby (ed.), The Luftwaffe and the War at Sea 1939-1945: As seen by officers of the Kriegsmarine and Luftwaffe (London: Chatham Publishing, 2005), 179-185. [6] E. D. Webb, HMS Vernon, 1930-1955. (HMS Vernon: The Wardroom Mess Committee, 1956), 20-25. [7] Peter Elliot, Allied Minesweeping in World War 2. (Patrick Stephens: Cambridge, 1979), 30-34. For more information specifically on motor minesweepers see: Michael J. Melvin, Minesweeper: The Role of the Motor Minesweeper in World War II (Worcester: Square One Publications, 1992). [8] An influence mine is a device triggered using sensors to detect the presence of a vessel when it comes into range of the mine’s blast. [9] Alfred Thayer Mahan. Influence of Sea Power upon History, 1660-1783 (Scotts Valley: Createspace Independent Publishing Platform, 2016), 7-15.
Excellent article Jack. You might want to check out my Twitter account @Sweepers3945 ; we appear to be sweeping the same channel (albeit employing different techniques!)