Pretty self explanatory. I've read accounts of almost all of the nations that participated in the battle/fall of France during WW2, from Brits at Dunkirk to German tank commanders, but I can't think of a single one (other than DeGaulle's memoirs) from the individual French soldier's perspective of that time, or his experiences fighting the impossible.
I know that the entire "hahahah French surrender monkies" narrative does a real disservice to what the French military and people went through, and I've heard of accounts of really epic bravery and daring. Just wondering how life would've been for a grunt having to fight that battle, and hoping there's some obscure journals or something that I could read into to get that bit of history.
First one that comes to mind is Pilote de Guerre by Antoine de Saint-Exupéry (1942). Saint-Exupéry was of course the famous French Air Force pilot who wrote le Petit Prince. This book is written as telling the story of a reconnaissance flight he undertook during the 1940 campaign, but really during the flight he reflects on the coming defeat. It's a good book to get a glimpse of the atmosphere after the first collapse and retreat.
There is of course Strange Defeat by Marc Bloch. The writer wrote this book just after returning from the 1940 campaign in an attempt to find out what went wrong and why France collapsed so suddenly and unexpectedly. Of course it's not the individual soldier story you are looking for, but it is a French perspective on the Battle of France written by someone who was present as soldier.