Maxyboy, French player here.
Just a few observations from the defense and fall of France. I was quite happy about the amount of troops I managed to pour out. Due to some increased production from my land gains in Germany and some fairly prolongued fighting in France I actually buildt almost all of my manpower. Sadly some of it didn't come to use as they were defending VP's in inner France.
In a joint allied effort we did hold the front for quite some time. Especially west of Paris. It was the following shift of troop to eastern France that I didn't react to to fast enough. Well played Germany. As I was a bit late, I didn't quite get the defensive positions I should and that part of the front crumbled a lot faster than intended.
The threat from Spain did tie up a lot of forces, but as the conflict continued without Italian intervention those forces was shifted towards Paris. When Paris fell, only a few token defenders was left on the Spanish border.