The French fought hard. The problem was twofold:

1. The German army in 1940 was utterly unstoppable. They didn't just conquer France, they conquered half of Europe. The French army was seen as the best army in the world at the time, but they were utterly unprepared for the new way of warfare the Germans introduced.

2. Petain.

Had the channel not been there, the UK would have surrendered like the French…

Been like this since the 100 years war... Some tourism on the continent or else, then run back to the security of their island if any trouble. And spitting their British exceptionalism contempt across the channel and the rest at any occasion. Our best "friends".