My Grandfather was a Methodist minister before he went off to WWI to do his spiritual job for the troops. When he came back he left the church saying 'There is no God.' When anyone ever asked him about WWI his answer was always the same. 'There is no God.' That was all he ever had to say about WWI.
My Uncle Al was a Sherman flail tank driver; he landed on D Day and fought in every major battle up until Bastogne when his tank was hit, he was the only survivor although badly burned. He never talked about his time in the war except to his wife, my Aunt Maj who was a WAAF driver at Elvington during the war, used to drive the crews out to the bombers, she is still with us and bright as a button.
On the other hand my Uncle Roy who fought with the RA in Italy on Auster spotters would talk the hind legs off a donkey. He was a quiet man generally but all you had to do was mention something like 'When were the Anzio landings, I can't remember' and he would look into the distance and talk for hours.
Different folks, different strokes I suppose.