Yes, they did.
They lost about what the Russians did, proportionally, in World War II.
Ils ne paseront pas!
And they did not pass.
But look how far, how fast a great nation can fall due to nothing more than the change of mind of some people.
Ozymandius.
Losing so many young men is what changed them. The memory of that carnage altered their outlook on war. Some villages lost all the young men in them. That's why they were called the "lost" generation long before that term was applied to their slacker descendents.