system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do Americans insist that the French are a bunch of cowards?

I can't join the military in the US due to my criminal record so I decided to up my training and volunteer in the Legion. I mentioned it at a dive bar (big mistake) and there was a resounding number of people who detested my decision, saying "Why would you want to join a bunch of cowards like that? They're just going to surrender!" 

I'm kind of confused because it was my understanding that the French helped during the Revolutionary War. Are there other reasons that I wasn't made aware of during history class? Was it all over WWII?

(Obviously not all US citizens adopt this mindset but the people in my area who do are numerous.)

Edit: Thanks for all the responses! From the gist of it I am assuming that all this shit talking is friendly banter. And when shit gets real we would have each others back. I'll leave this open for another hour just so I can read through more of the comments. Also just in case anyone else chimes in with something that was not already mentioned. 

Edit 2: Alright this is starting to sound like the old farts at the bar got Reddit accounts. Thanks for the explanations folks.
gpt
I'll explain it like you're 5. America, France, England. Were kinda all these arrogant buddies. We give each other shit but mostly got each other's backs. France is a tough bastard but one time in middle school he got in a fight with Germany. Germany had just finished Karate class. Instead of getting his ass kicked France said fuck it and went home. Now USA makes fun of France. "Dude France, it's okay...you don't have to surrender!"
And France is all like "dude that was one time in middle school!"