Hi All,
I am a naval architect/marine engineer (I design ships for a living) with a strong interest in icebreaker design. Additionally, I used to work in the Great Lakes region of the United States, which has a proud history of using icebreakers to extend the shipping season for iron, coal, and other products on the Great Lakes, which freeze over entirely from mid-December to Mid-March or April, depending on the year.
Without a doubt, the most famous Great Lakes icebreaker was the USCGC "Mackinaw" (WAGB-83, not its successor the WLBB-30), which was purpose built in 1943-1944 to break ice on the Great Lakes. It's well known in the Great Lakes region that the reason for the construction of the Mackinaw was to ensure continuous shipments of iron ore from the Mesabi Range of Minnesota and the shipments of native copper from the Upper Peninsula of Michigan during wartime. On the whole, the USCGC Mackinaw was a critical piece of infrastructure that ensured US Steel Mills and US copper refineries would keep running at maximum production throughout WWII.
Apologies for the long introduction, but that context is necessary to introduce my main question: if Germany's wartime steel industry was also reliant on distant shipments of iron ore from over oft-frozen seas like the US (in Germany's case, shipments coming primarily from Sweden's iron ore mines at the northern end of the gulf of Bothnia of the Baltic Sea, which freezes over from December to April), then why didn't Germany build any icebreakers like the United States? For the most part, Germany's winter iron ore shipments had to come down the coast of Norway (which does not freeze over in winter), which resulted in the loss of many German ships to frequent and ferocious Allied naval attacks.
I would be very appreciative of any insight or literature about this question from real historians. And while I am not a historian myself by any means, my main theory about this question is that it is a chicken-and-egg situation: Germany didn't consider using icebreakers, the lack of which hampered Germany's steel production significantly, so the US learned from Germany's mistakes and decided to protect their iron ore shipping by building icebreakers. I would be very appreciative if anyone with an interest in historical naval architecture or wartime logistics concerns could weigh in on this question.
The northern Swedish iron ore was railroaded east in summer, to Luleå, where it would be loaded on ships and transported to the customers of the Swedish state ore company LKAB. The eastern part of this railroad was finished in 1888.
In winter, the port of Luleå would freeze "in" (more on this later) and the ore would then be railroaded west to the port of Narvik, which was ice-free even in winter. This part of the railroad was finished i 1903.
The customers for the ore extracted in Gällivare and Kiruna included not only the German steel mills in the Ruhr area, but also British steel mills on the eastern coast of the British isles. In 1927, the British bought roughly 7 million tons of iron ore yearly, while the Germans bought 10 million tons and were agreed through trade deals between Sweden and Germany and Britain (despite the trade deals, this would fluctuate wildly in the coming years, with the British especially unable to meet their quota due to the Great Depression).
The infrastructure and transport paths of the iron ore was there before it became a vital war supply for the Germans, and worked fine in peace-time.
It should also be said that before the war, the German steel mills imported plenty of iron ore from France, primarily from the mines in Alsace-Lorraine (which had been German territory between 1871 and 1919) and they would again after these mines had been captured by the Germans in summer 1940.
Thus, before the war the ordinary infrastructure to get ore to the German steel mills (barges on the Rhine and shipping from Luleå or Narvik) worked fine. You can say many things about the nazi government, but their long-term planning for how to be supplied with raw materials was pretty much non-existant.
The fighting in Narvik in April and May 1940 ruined the ore loading facilities in the port of Narvik, and the British navy made it hard to ship iron ore over the North Sea throughout the war.
However, ice breakers would probably not have been the solution - both Finland and Sweden had large and strong ice-breakers, but ice-breaking over sea is a very different affair to ice-breaking over lakes. The Gulf of Bothnia has strong currents and the normal movement of an ocean makes a massive ice cover that simply needs breaking and then a lane to be kept from freezing over again like on a lake rare.
Normally, ice flakes would move through the force of wind, waves and currents and pile up, sometimes in enormous hills that were unbreakable even by the largest and most powerful icebreakers. This is why I use "in" rather than "over" when the ports would freeze during winter.
See for example the ice piled up in the harbour of Helsinborg in February 1940. This was after a very harsh winter, but much further to the south. This is how Luleå could look in winter every year.
The bottom line is that Sweden and Finland, who had large powerful ice-breakers and plenty of experience handling ice conditions in their Baltic Sea ports knew that keeping them open during winter was impossible - even with top-notch powerful large icebreakers such as the Swedish HMS Ymer (you can see the difficulty of sea icebreaking in this image) from 1932.
The solution to the problem during the war was to railroad the iron ore down to Oxelösund, slightly south of Stockholm, from which the Swedish ice-breakers could keep a path open (during normal winters anyway) and to stockpile ore before the ports froze "in". This put a large strain on the Swedish railway network, but since the Swedish railway network was electrified, it did not cause a much larger need for fuel, and the Germans were very keen on Swedish iron ore deliveries and made sure to deliver coal to Sweden as long as trade kept up (until October 1944).
