Personally I can only see any difference if the harbours had been taken and got in use in short time period ( Dieppe, Calais, Antwerp etc ) because during the real WW2 the speed element was enough to get the forces to the German border/ river Rhine but then they had to stop by autumn 1944 simply because the troops could not be supplied. So changing the troops without changing the supply element would not change much in my opinion.

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