Operation Royal Marine

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Operation Royal Marine
Part of the Second World War
Map commune FR insee code 67472.png
Soufflenheim and vicinity
Operational scopeTactical
Rhine, Moselle, Meuse rivers

48°50′N 7°58′E / 48.83°N 7.96°E / 48.83; 7.96Coordinates: 48°50′N 7°58′E / 48.83°N 7.96°E / 48.83; 7.96
Planned byWinston Churchill
Commanded byCommander G. R. S. Wellby.
Objectiveobstructing German rivers and canals with fluvial mines
DateOctober 1940 (1940-10)
Executed byMilitary Intelligence Research [MIR(c)], Royal Navy parties
OutcomeTemporary suspensions of German river traffic and damage to barge barriers and bridges
Sufflenheim is located in France
Soufflenheim, a commune in the Bas-Rhin department of north-eastern France

Operation Royal Marine was a military operation in May 1940 of the Second World War, during the Battle of France (10 May – 25 June 1940). The British floated Fluvial mines down rivers which flowed into Germany from France. The plan was to destroy German bridges, barges and other water transport. After several postponements insisted on by the French government, fearful of German retaliation, the operation began on 10 May 1940, when the German offensive in the west began. The mines caused some damage and delay to German river traffic on the Rhine from Karlsruhe to Koblenz and damaged bridges and protective barriers. Part of the plan was for Royal Air Force (RAF) bombers to drop the mines into rivers and canals on moonlit nights but this had hardly begun when the campaign ended. The success of the plot was nullified by the Allied defeat and the Franco-German Armistice of 22 June 1940.


Despite the concerns of the French government during the Phoney War, over German air attacks and reprisals against French waterways, it was intended that the operation would take place simultaneously with Operation Wilfred, a scheme to mine the waters around Norway. The novelty of Operation Royal Marine was intended to divert American attention from the possible illegality of Operation Wilfred.[1] Wilfred was to force German convoys transporting Swedish iron ore into international waters, where they could be attacked by the Royal Navy.[2]

Simultaneous attacks with fluvial (river) mines against Germany was intended to deflect criticism that the Allies were not making war on Germany but the small countries around it, that they claimed to be protecting. A decision of the Anglo French Supreme War Council was taken on 28 March 1940 to commence Operation Royal Marine on 4 April and the air-dropping of mines on 15 April. The decision was vetoed shortly afterwards by the French War Committee, a ruling which was not rescinded for about three months.[3] Operation Wilfred was left to take place on its own on 5 April and was then postponed to 8 April, later parts of the plan being cancelled when news arrived that the German fleet had sailed.[4] The British and French were able to agree that Operation Royal Marine could begin as soon as the German offensive in the west commenced.[5]



Course of the Rhine (Post-1945 borders of Germany.)

The plan had been presented to the British Cabinet in November 1939 by Winston Churchill, as a means of retaliation against illegal German minelaying.[6] (Sir Edward Spears claimed that he had originally proposed the idea to Churchill, when they visited eastern France in August 1939 but by the time the operation began, Churchill believed the idea to be his.)[7] A stock of 2,000 fluvial mines, with 1,000 more being produced per week, were to be put into rivers in France that flowed into western Germany, by naval parties led by Commander G. R. S. Wellby. The sailors were to be based in the Maginot Line, about 5 mi (8.0 km) distant from the Rhine, to put mines in the river, interfering with commercial traffic for 100 mi (160 km) beyond Karlsruhe.[8] The mines would sabotage barge traffic and other river craft but become inert before reaching neutral territory at the Netherlands border. On 6 March 1940, the Cabinet was notified that mines would be ready for release from riverbanks on 12 March and to be dropped by RAF bombers by mid-April, between Bingen am Rhein and Koblenz on moonlit nights. Neutrals were to be warned and the first 300–400 fluvial mines were ready by the night of 14/15 March; after French objections for fear of German retaliation, the plan was postponed.[6] In April, Churchill tried to persuade the French to drop their objections to Royal Marine and remarked after meeting the Prime Minister of France, Édouard Daladier Nous allons perdre l'omnibus.[9]


The mines were specially developed for the operation by Ministry of Defence 1 (MD1, Churchill's Toyshop), a British weapon research and development organisation.[10] Each mine contained 15 lb (7 kg) of Trinitrotoluene (TNT). Trials of the mines were carried out in the Thames in December 1939 and depending upon type, either floated or bounced along the riverbed.[11]


On 10 May 1940, mines were released into the Moselle to destroy pontoon bridges built by German army engineers; other mines were put into the Rhine to negligible effect.[12] On 13 May, the British put 1,700 mines in the Rhine near Soufflenheim, reported by General Victor Bourret, the Fifth Army commander, to have caused damage to the barge barrier protecting the bridge at Karlsruhe. Several pontoon bridges were damaged and river traffic was temporarily suspended between Karlsruhe and Mainz.[13] By 24 May, over 2,300 mines had been released into the Rhine, Moselle and Meuse rivers.[14] On 9 June, General de Armée Andre-Gaston Pretelat, commander of Groupe d'Armée 2, ordered the fluvial mines to be sent down the Rhine to delay a German attack on the Maginot Line.[15] RAF Bomber Command mine dropping began between Bingen and Koblenz and into canals and river estuaries feeding the Heligoland Bight but few mines were laid by aircraft before the Battle of France ended; any damage caused could not be measured.[16]


In Assignment to Catastrophe (1954), Edward Spears, the representative of Churchill to the French Prime Minister, who had first mooted the mining of German rivers in 1939, quoted Churchill from Their Finest Hour (1949) that,

The success of the device was, however, lost in the deluge of disaster.

— Churchill[17]


  1. ^ Derry 2004, p. 24.
  2. ^ Roskill 1957, p. 156.
  3. ^ Butler 1971, pp. 122–123.
  4. ^ Roskill 1957, pp. 156–158; Derry 2004, pp. 25–26.
  5. ^ Butler 1971, pp. 181–182.
  6. ^ a b Butler 1971, p. 114.
  7. ^ Spears 1954, p. 21.
  8. ^ Ellis 2004, p. 52; Spears 1954, p. 21.
  9. ^ Spears 1954, pp. 104–105.
  10. ^ Macrae 1971, p. 31–51.
  11. ^ Telegraph 2003.
  12. ^ Rowe 1959, pp. 138–139.
  13. ^ Spears 1954, p. 149; Rowe 1959, pp. 155; Butler 1971, pp. 181–182; Churchill 2005, p. 36.
  14. ^ Ellis 2004, p. 52.
  15. ^ Rowe 1959, pp. 237.
  16. ^ Churchill 2005a, p. 647; Ellis 2004, p. 53.
  17. ^ Spears 1954, p. 149.



  • Butler, J. R. M. (1971) [1957]. Grand Strategy: September 1939 – June 1941. History of the Second World War United Kingdom Military Series. II (2nd ed.). HMSO. ISBN 978-0-11-630095-9.
  • Churchill, Winston (2005) [1948]. "Appendix Q - Operation Royal Marine - Note by the First Lord of the Admiralty, March 4, 1940". The Second World War: The Gathering Storm. I (Penguin Classics ed.). Boston: Houghton Mifflin. ISBN 978-0-14-008611-9.
  • Churchill, Winston (2005) [1949]. The Second World War: Their Finest Hour. II (Penguin Classics ed.). Boston: Houghton Mifflin. ISBN 978-0-14-008612-6.
  • Derry, T. K. (2004) [1952]. Butler, J. R. M. (ed.). The Campaign in Norway. History of the Second World War, United Kingdom Military Series (Naval & Military Press ed.). London: HMSO. ISBN 978-1-84574-057-3. Retrieved 7 February 2016.
  • Ellis, Major L. F. (2004) [1st. pub. HMSO 1954]. "The Counter-Attack at Arras". In Butler, J. R. M. (ed.). The War in France and Flanders 1939–1940. History of the Second World War United Kingdom Military Series. Naval & Military Press. ISBN 978-1-84574-056-6. Retrieved 7 February 2016.
  • Macrae, Stuart (1971). Winston Churchill's Toyshop. Kineton: Roundwood Press. OCLC 603643856.
  • Roskill, S. W. (1957) [1954]. Butler, J. R. M. (ed.). The Defensive. History of the Second World War United Kingdom Military Series: The War at Sea 1939–1945. I (4th impr. ed.). London: HMSO. OCLC 881709135. Retrieved 21 December 2015.
  • Rowe, V. (1959). The Great Wall of France: The Triumph of the Maginot Line (1st ed.). London: Putnam. OCLC 773604722.
  • Spears, Sir Edward (1954). Assignment to Catastrophe: Prelude to Dunkirk. July 1939 – May 1940. I. London: Heinemann. OCLC 929260462.


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