As for their caving in, just like their descendants in WWII:
1. The French fought a great many wars (probably hundreds) over the last thousand years or so. Of those wars, they were ignominiously defeated in exactly one. They didn't always win, but they always fought bravely. Not a bad record, overall.
2. Caesar, perhaps the greatest military mind leading the most perfectly adapted military machine in history, took eight years (I think) to conquer the Gauls. Of the six million Gauls, at the end of the war perhaps 2,000,000 were dead and another million had been sold into slavery.
So much for ignominious surrender. They were defeated by superior technology and (especially) discipline. Nobody, especially the Romans, ever claimed they weren't brave.
Caesar is very clear that Gaul was not a united nation, but had a multitude of separate, frequently warring tribes. They all spoke related languages and were at least as much a "nation" as were the Greeks of the same era, who thought of themselves as a single people even though they had many separate governments.
Would that be the Franco-Prussian war, or WWII?
Let's not forget the battle of Tours, and Charles Martel, which gave the expanding Islamic empire a great bloody nose.
We may joke a lot about the french, but the facts of history (as you point out) tell a very different story.
Oh yes, and let's not forget that a great many vikings settled in Saxony, and became part of the genetic mix known as the french.