The
Cheese Eating Surrender Monkeys trope comes from the fact that the french submitted to the German invasion force very quickly during world war 2. the
reason for this is that their infrastructure and economy got
rocked by the fact that they were one of the major forces during World War 1. Prior to this they were a world superpower for
centuries, easily on par with the British empire, and in fact had a fierce rivavlry with them wherein they won easily as many wars as they lost. And that's ignoring all the other wars they were in during those same centuries.
Not to mention the french were still
incredibly useful during world war 2. The french rebels successfully forced Germany to station a lot more troops there than they would have otherwise. Even after surrendering, the french were still fighting. Yes, I do not care for that trope.
Honestly, the prevalence of it is America's fault - the British like to poke fun at the french, yeah, but they never do it seriously. The Americans seem to legitimately believe that the french are the worlds biggest cowards.. I'm sorry to the american's here, but your approach to history just bugs me. I've heard about a Canadian who went to Texas to study, and his history professor taught the class that
America won world war 2. Like, alone. Because they came in at the last moments and carved a path to Berlin, leaving the rest of the world to clean up their messes.