My father wouldn’t talk much about the war, either. He enlisted in the Marines right after Pearl Harbor, as many men did - even though he was slightly over the age when he might have been drafted.
All the story I know comes from his mother, my Grandmother, that he was ‘at’ Iwo. I gathered later that he was on some kind of ship that lent support.
I have read a lot and interviewed men who had fought in wars.
They never want to talk about it.