I first meant this post to talk about long-term after the fact effects of combat, how it changes the warrior who fights in battle permanently. But I've found the actual information on this topic more elusive than I believed it was. So I'm going to broaden the topic a bit to talk about the effects of combat after the fact in general, not just long-term.
Let's start with the "thousand yard stare." I read one source that suggested that eyes staring unfocused in the distance is adaptive for survival, because by not focusing on any particular thing, the peripheral vision expands, so any potentially dangerous motion is easily detected. I mention this source more to illustrate that many of the actual realities of why human beings do what they do under various circumstances is in fact still at least partially a matter of speculation. And sometimes a whole lot more than "partially" speculative.
Unlike the source I just quoted, I think it's more normal to see the thousand yard stare as a product of information overload to the brain. Normal eye movement, normal inquisitive engagement of the environment ceases, because the brain has seen enough and engaged enough. It may be true a person in that state defaults to a form of vision designed to pick up motion, but the primary reason for such a reaction is sensory and emotional overload.
Such a state of staring is usually temporary, as are all the effects of what is now commonly called a "Combat Stress Reaction." In addition to the stare, troops coming off prolonged hard fighting tend to share the following traits:
The slowing of reaction time
Slowness of thought
Difficulty prioritizing tasks
Difficulty initiating routine tasks
Preoccupation with minor issues and familiar tasks
Indecision and lack of concentration
Loss of initiative with fatigue
Inability to relax
Shaking and tremors
Nausea and vomiting
Loss of appetite
Frequency of urination
Heightened sense of threat
Loss of adaptability
Mistrust of others
Extreme feeling of losing control
Obviously not everyone experiences all of these traits. In fact, many of these reactions are opposites, e.g. excessive sleep versus insomnia. For most people exposed to combat, a number of these reactions (but not all) are normal. And for most warriors, the bulk of these effects fade after a few days. The experience of US Military medicine in WWII indicated that a person was in fact more likely to fully recover if after only a short break he returned to his unit and continued to engage in combat. Why this is true is a matter of speculation, but it may be the case that someone who disengages from combat stress can see himself as a permanent failure if not allowed to return to duty with "the rest of the normal soldiers."
Acute combat reactions are fairly well understood. Most people experience them if under enough combat stress--that amounts to something like 96% to 98% of all modern combat soldiers, with a very small group of exceptions, as previously noted in edition 2 of this series on combat realism in stories, The Fearless Elite.
The list of effects I copied above starts to fade into longer term effects when it lists depression, substance abuse, loss of adaptability, attempted suicides, disruptive behavior, and mistrust of others. These particular traits can become long-term conditions. And acute reactions, from nightmares, to depression, h, heart palpations, and more, can occur in someone who has been long removed from combat if something occurs that triggers the memories of warfare. A mild example would be how I for a long while after returning from Iraq (where I was subjected to rocket attacks over a long period) would "excessive startle" at loud banging noises from firecrackers to slamming doors.
Other reactions include a sense that life outside of combat is ridiculously trivial, which is understandable when dealing with life and death in war versus dealing with running errands in regular life. In addition, a person who has experienced extremes of emotion on the battlefield often shows signs of emotions being fused in ordinary life. So a person can rapidly become angry or experience other rapid shifts of emotion. I found myself experiencing some of the sense that ordinary life doesn't matter much, as well as quicker-than-normal anger.
My reactions, such as they were, faded in me over a period of several years. And they do fade for most people, but for many, never very much. True stories of veterans who suffer from nightmares, or who can not be safely awakened unexpectedly in the middle of the night, or who always sit in the corners of restaurants to keep an eye on an entire room are extremely common.
Historical accounts of medieval behavior, in which knights seem to show very little emotional control are also well known to historians. That is, they seem to have demonstrated signs of the kind of emotional swings experienced by someone exposed to traumatic stress. Please note that these stresses are not limited to combat--people can experience this from other kinds of trauma, especially when they are exposed to it as children. Please note that many children in the medieval world were exposed to violent trauma--and this would also be common in many worlds of epic fantasy.
What exactly is the connection between acute combat reactions and long-term post traumatic stress is difficult to say in a broadly meaningful way. Some people have a greater tendency to deal with long-term problems than others, though why isn't clear. Note though that a person is not necessarily disabled by continuing to have a post-traumatic reaction. People can have sudden unexpected reactions to certain smells or sounds or other stimuli that remind them of their combat stress without being paralyzed by such reactions. People can suffer from black moods and have suicidal thoughts and overcome such conditions, especially with help from others who have gone through the same sorts of things. In fact, it's important for veterans to realize such reactions are to a degree, normal, and to talk to one another, or at times to professionals, about their experiences is healthy and good.
One factor that seems to relate to how soldiers react to combat over the long-term stems from whether people are able to justify their actions in combat to themselves. A person who looks back and feels he acted morally, correctly, does much better in dealing with post traumatic stress than those who look at back at their own behavior and see it as reprehensible. Note the sense of "morality" I'm referencing does not necessarily mean a person is good--a knight judging his actions from a warped view of Christianity may have felt morally justified in killing defenseless Muslims and Pagans--that doesn't mean he actually was justified in a broader moral sense. But the ability to feel justified has always helped warriors deal with the aftermath of combat. Those who cannot justify their actions to themselves have a harder time.
Note also there is a difference between having post traumatic stress or a post traumatic stress reaction and having PTSD--Post Traumatic Stress Disorder. The disorder occurs when veterans are disabled by their experiences, when their lives are interrupted significantly. A person can have a certain amount of permanent effects from combat--it is normal in fact to have some--while still functioning in life in a normal way. Or mostly normal...
Stories that include combat should reflect these realities.
Since this post addressed psychological reactions to combat stresses after combat, for the next installment of this series I'll discuss psychological and physiological reactions to stress during combat.