Sophocles wrote about a mentally scarred Greek warrior in
Ajax. That was like, 400 BC. I think the guy you're talking about is
Geoffroi de Charny. Good ol' Jeff gone through some seriously rough shit, like POW'd twice and dissecting an enemy leader and hanging the remains on castle gate.
The crusades must of been pretty scary too. I remember reading something like, 1/3 of all crusaders died before reaching Jerusalem. Not to mention the other joys of expeditionary warfare; diseases, lack of provisions, uncomfortable climates etc.
One thing the knights didn't have was the Geneva Convention. Sure, there's the code of chivalry and everything related to it. But some of the stress a modern soldier faces when causing collateral damage is the social taboo brought on by treaties and conventions signed in recent times. In other words, with no governing laws telling you massacres are wrong, there's less pressure as a whole to be repulsed by it.
Comparing knights and the warfighters of today, I think we have some parallels. Sure, the knight is raised from birth to fight. But the US Army private in Vietnam receives basic training to condition his mentality. Although that's nothing compared to a martial lifestyle, the basic training builds upon the experiences of many generations and is much more condensed. Remember that much of the historical accounts have been lost to time, and for a subject not scientifically investigated until WW1, it is especially prone to be overlooked.
Anyways, we're on a hot topic and not one easy to stomach. After all, we're writing fiction about a fictional, fantasy world. Straying a bit from 100% historical accuracy is perfectly acceptable.
