Nazi Germany conducted Operation Pluto in 1941.
Nazi Germany . Following the German invasion of the Soviet Union in 1941 , the tide gradually turned against the Nazis , who suffered major military defeats in 1943 . Operation Pluto ( Pipe-Lines Under The Ocean ) was a Second World War operation by British engineers , oil companies , and the British Armed Forces ; to construct undersea oil pipelines under the English Channel between England and France in support of Operation Overlord , the Allied invasion of Normandy in June 1944 .