To me it seems ever since the Poland invasion the German Army lived only through winning and conquering. Thus they got more resources without which the capability of fighting a (long) war was not possible. I think even by summer 1942 the German(!) workers of the Reich were still doing one shift working system, if I recall correctly it was changed from 8 hours to 10 hours though, but just think what everyone else did since 1940 or earlier!

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