“Do not underestimate the French.”
You quite rightly cite Verdun as a terrible battle for the French, however, a lot has passed since WWI.
WWII
Algeria
Vietnam (First Indo-China War)
Syria
Lebanon
Madagascar
Morrocco
All lost by the French since WWI, as I remember.
I don’t know that people ARE underestimating the French here. It may just be possible that you’re OVERestimating the French.