. My grand-father battled in WW2. He never ever spoke a single word about it. Nada. Actually he barely spoke to anyone at all all his life afterwards.
I have read about this. They even address this in the documentary. The veterans said that the civilians and those that didn't serve at the front just couldn't relate to what the veterans. One vet even said his own father couldn't relate. He said that every conception that his father had was incorrect. The civilians realized this over time and stopped trying to talk to the veterans because it was awkward. The veterans said that they could only talk about the war with other veterans.
Realize that the British lost 3 men in WWI for every man they lost in WWII. They lost just under a million men. I believe it was about 900 thousand.
The French and their "Cult of the Offensive" misguided philosophy that did not work against contemporary battlefield technologies cost them 1.4 MM war dead!
The German's lost 1.8 Million men and the Italians that were courted by both sides and got a better deal from the Entente got into WWI late for territorial gains lost 650 thousand.