Swedish iron ore during World War II

Swedish iron ore was an important economic factor in the European Theatre of World War II. Both the Allies and the Third Reich were keen on the control of the mining district in northernmost Sweden, surrounding the mining towns of Gällivare and Kiruna. The importance of this issue increased after other sources were cut off from Germany by the British sea blockade during the Battle of the Atlantic. Both the planned Anglo-French support of Finland in the Winter War, and the following German occupation of Denmark and Norway (Operation Weserübung) were to a large extent motivated by the wish to deny their respective enemies iron critical for wartime production of steel.

Winston Churchill, then First Lord of the Admiralty, was particularly concerned about Swedish exports of iron ore to Germany, and pushed for the British government to take military action to end the trade. From the beginning of the war Churchill tried to persuade his cabinet colleagues to send a British fleet into the Baltic Sea to stop shipping reaching Germany from the two Swedish iron ore ports, Luleå and Oxelösund. The project was called Project Catherine and was planned by Admiral of the Fleet William Boyle, 12th Earl of Cork. However, events overtook this project and it was canceled. Later, when the Baltic ports froze over and the Germans began shipping the iron ore from the Norwegian port of Narvik, Churchill pushed for the Royal Navy to mine the west coast of Norway to prevent the Germans travelling inside neutral territorial waters to escape Allied Contraband Control measures.

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