Operation Rubble

The German invasion of Denmark and Norway, Operation Weserübung, in April 1940, effectively closed the Baltic Sea to shipping and denied the British access to Swedish iron and steel products.

Shortly before leaving the country, King Haakon VII of Norway had approved legislation which requisitioned all Norwegian shipping under the control of a directorate called Nortraship based in London.

Blinney suspected that the minefield was not as comprehensive as the Germans had claimed and with the encouragement of London, chartered a small Finnish tramp steamer, Lahti, to attempt the run.

Departing Gothenburg on 5 July 1940 carrying 300 tons of steel products, Lahti successfully traversed the Skagerrak, however the short night allowed her to be spotted by German aircraft and her master obeyed their instruction to head for Kristiansand and internment, but the point had been proved.

Those Norwegians unwilling to take the risk were replaced by volunteers from the British Merchant and Royal Navy crews who had escaped from Norway and were held in an internment camp at Hälsingmo near Söderhamn in central Sweden.

[7][8] The ships successfully delivered approximately 18,600 metric tonnes of materiel including ball bearings, machine tools, spare parts, iron, ingots, and steels of various qualities.

[13] The same tactics were employed for Operation Moonshine starting in September 1944 which was largely frustrated by poor weather and mechanical defects; a single mission in January 1945 reached Sweden, although the two of the three boats involved collided, resulting in the loss of one of them.