There is always more to be said, but you may be interested in this past Monday Methods post by /u/hillsonghoods:
On why 'Did Ancient Warriors Get PTSD?' isn't such a simple question.
and this past answer by /u/Iphikrates:
Are there any examples of PTSD from early wars or time periods such as the Middle Ages? Especially in times where fighting and killing people was honorable and glorified?