I mean everything before the first world war. I just haven't heard any story about e.g. Roman legionnaires or British redcoats having such problems after returning home.
It's a complicated matter, made even more so by the inherent difficulty of psychoanalysing a long-dead person from a wholly different cultural background at a distance of years or centuries. u/Iphikrates examines the matter with a classical eye in this post, while u/hillsonghoods has a Monday Methods post on just why it's so complicated.