People should notice that resistance is stiffening and not just because of the logistics problems. The forts around Metz are occupied. Metz is in territory the Germans regard as German. It has been going back and forth since the Middle Ages, but from 1871 to 1919 it was in the German Empire and Hitler made it part of Germany again. So, the Germans are now fighting for home and hearth and naturally will stiffen along a much shorter front.
This is one of those times when knowing the future is depressing!