Excellent counterpoint from r/AskHistorians (paragraph breaks added for legibility): [1] > Cross-cultural psychologists have observed that, regardless of cultural background, people who suffer persistent emotional disturbances in the wake of a traumatic event exhibit intrusive memory symptoms in some form. Here in the US, these are closely related to what we commonly call "flashbacks." For the Romans, people experien…
One of the interesting comments from the AskHistorians FAQ on PTSD is that, in the classical world, PTSD like behaviour was more commonly associated with public shame rather than private guilt. They might have felt much less conflicted by killing because they did not come from a cultural background where killing your enemies is usually prohibited. Our justification as a culture for warfare starts with "of course, kil…
We have a very sanitised and romantic notion of war. Battles are framed as "historical events", not as personal experiences which would be considered horrific by most people today.
In medical terms we're talking about gangs of (usually) thousands of armed men people trying to cause as much death and injury to each other as possible through physical trauma, stabbing, dismemberment, burning, drowning, and disemboweling - with almost certain infection and sepsis for the survivors. And relentless peer pressure to participate.
Sociopaths might thrive in that environment, but anyone with any empathy would find it challenging. Even if they viewed the enemy as subhuman, they would still have to deal with the extreme personal stress and the direct personal experience of uncommon brutality.
And the losers would experience all of that mingled with the usual psychological effects of failing to win.