| Operation Royal Marine | |
|---|---|
| Part of the Second World War | |
 Soufflenheim and vicinity | |
| Operational scope | Tactical |
| Location | Rhine, Moselle, Meuse rivers 48°50′N 7°58′E / 48.83°N 7.96°E |
| Planned by | Winston Churchill |
| Commanded by | Commander G. R. S. Wellby |
| Objective | Obstructing German rivers and canals with fluvial mines |
| Date | May 1940 |
| Executed by | Military Intelligence Research [MIR(c)], Royal Navy parties |
| Outcome | Temporary suspensions of German river traffic and damage to barge barriers and bridges |
  Sufflenheim | |
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.