HMCS Thunder (J156)

The minesweeper was ordered as part of the 1939–40 building programme^[6] and the keel was laid down on 4 December 1940 by Dufferin Shipbuilding Co. at their yard in Toronto, Ontario. Thunder was launched on 19 March 1941 and commissioned at Toronto on 14 October 1941.^[7]

Thunder sailed for Halifax, Nova Scotia, arriving on 30 October and joined Sydney Force, the local escort and patrol force operating out of Sydney, Nova Scotia. In January 1942, the minesweeper transferred to the Western Local Escort Force as a convoy escort. The ship then bounced around among local forces, joining the Halifax Local Defence Force and then the Shelburne Force operating out of Shelburne, Nova Scotia, then back to Halifax Local Defence Force and finally Sydney Force.^[7]

The minesweeper sailed to Europe via the Azores in February 1944 as part of the Canadian contribution to the invasion of Normandy. After arriving on 13 March, the minesweeper was assigned to the 32nd Minesweeping Flotilla as the Senior Officer's Ship.^[7] Thunder transferred to the British 4th Minesweeping Flotilla in May.^[7][8] During D-day operations, the 4th Minesweeping Flotilla was assigned to sweep assault channel 4 in the American sector.^[9][10] Once that was completed the 4th Minesweeping Flotilla was ordered to sweep between the channels 3 and 4.^[11] Thunder and the 4th Minesweeping Flotilla continued their minesweeping duties off Normandy until 6 June, when they sailed back to Portland to sweep a new minefield that had been laid in the approaches to the harbour.^[12] This took the flotilla ten days to complete, after which Thunder was ordered to join American minesweepers for the assault on Cherbourg.^[13]

On 24 June, during the preliminary bombardment, the minesweeping force of which Thunder was a member, arrived off Point Barfleur in mid-afternoon. German shore-based gunfire began to splash down around the minesweepers after an hour, leading the escorting United States Navy destroyers to deploy a smokescreen and order the minesweepers to cut sweeps and retire. The following day during the assault, the minesweepers were deployed again. Shore-based gunfire began raining down on the minesweepers again. Thunder was hit by shrapnel from a near miss and the destroyers were once again forced to lay a smokescreen.^[14][15]

Thunder returned to Canada in August 1944 to undergo a refit at Sydney. The minesweeper returned to European waters in November and was assigned to the 31st Minesweeping Flotilla.^[7] In April 1945, the 31st Minesweeping Flotilla was assigned to the last large-scale combined operation in the European theatre. Sailing to the Gironde estuary on 12 April, the minesweeping flotilla swept an invasion channel for the attack force landing in the area. Once their minesweeping duties were completed, the minesweepers performed an anti-submarine patrol in the area. They continued in these duties until 16 April when the minesweepers returned to Plymouth. While transiting the Bay of Biscay, Thunder accepted the surrender of the German auxiliary minesweeper FGi 07 and with a prize crew aboard, took the vessel back to the United Kingdom.^[7][16] Thunder and the 31st Minesweeping Flotilla spent the next five months sweeping the English Channel.^[17] Thunder remained in European waters until September, when the minesweeper returned to Canada. Thunder was paid off on 4 October 1945 and laid up.^[7] The ship was sold to Marine Industries in 1947 and broken up at Sorel, Quebec.^[7][18]

• Chesneau, Roger, ed. (1980). Conway's All the World's Fighting Ships 1922–1946. Greenwich, UK: Conway Maritime Press. ISBN 0-85177-146-7.
• Colledge, J. J.; Warlow, Ben (2006) [1969]. Ships of the Royal Navy: The Complete Record of All Fighting Ships of the Royal Navy from the 15th Century to the Present (3rd Rev ed.). London: Chatham Publishing. ISBN 978-1-86176-281-8. OCLC 67375475.
• Douglas, W.A.B.; Sarty, Roger; Whitby, Michael (2007). A Blue Water Navy: The Official Operational History of the Royal Canadian Navy in the Second World War, 1943–1945 Volume II, Part II. St. Catharines, Ontario: Vanwell Publishing. ISBN 978-1-55125-069-4.
• Macpherson, Ken; Barrie, Ron (2002). The Ships of Canada's Naval Forces 1910–2002 (Third ed.). St. Catharines, Ontario: Vanwell Publishing. ISBN 1-55125-072-1.
• Macpherson, Ken (1997). Minesweepers of the Royal Canadian Navy 1938–1945. St. Catharines, Ontario: Vanwell Publishing. ISBN 0-920277-55-1.
• Schull, Joseph (1961). The Far Distant Ships: An Official Account of Canadian Naval Operations in the Second World War. Ottawa: Queen's Printer. OCLC 19974782.

• "Bangor Class". Canadian Navy of Yesterday and Today. Hazegray.org.
• "HMCS Thunder (J 156)". Uboat.net.