FRANCE : country population - Historical demography
There are about 5 Germans for every 3 French citizens in 1940 (might add Austria.)
Note the birthrates? WWI was devastating for the recruiting cohorts from 1936 on.
1. Might add the left/right political divide.
2. Confused aviation policy.
3. Franco-British diplomatic troubles.
4. Confused industrial policy.
5. Loss of nerve as war approached. (The French are BRAVE, but their leadership (Emphasis on that word "leadership"); was split and confused as to what the war was about and why it should be prosecuted, never mind HOW it should be prosecuted.).
I do not buy into the myth of incompetence. Once the fighting started, the French climbed a steep learning curve faster than the Russians did. What hurt France is that they ran out of time and territory. Once the Germans reached the Seine and the industrial heart of France was in Berlin's hands, what was the French government to do? Fight on from the colonies? With what? I'm not that kind of critic. I'm a lessons learned guy. The French did the best they could with the handicaps they were handed.
I doubt anyone could have done better. Imagine how well the Americans could have done given that situation? Not very well, since they were boloed in 1940 (See 1-5) worse than France. I cannot emphasize how much Britain in 1940 with a successful air defense behind her natural moat and Russia as a giant land sponge in 1941 bought the 2 years time for everyone involved to learn how to beat the Germans. Remark that the French in 1944 once they were reconstituted, did a lot better and actually made fewer tactical mistakes in France 1944 than the other allies did.