What was the medieval view of PTSD? Any recognition, however limited, of the phenomenon? Have any 1st person accounts (eg. diary entries, paintings, poems) survived to today?
Man, I am nowhere near an expert enough to give you a good answer. But to the best of my knowledge, medieval society viewed what we could call PTSD through the lens of the virtues and vices – namely courage and cowardice, or courage and wrath.
And that kind of attitude was pretty dominant up to and through WWI – it took a while for the army hierarchy, let alone the wider society, to understand that “shell shock” was something different from cowardice. There was a lot of resistance to it being categorized as a medical or mental health condition, but the sheer incidence of “shell shock” meant that, eventually it had to be dealt with.
WWII brought something of a better understanding – more effort was put into gathering statistics, and psychologists working for the armed forces put forward convincing arguments that, rather than indicative of a failing of character (which harkens back to the medieval understanding), “battle fatigue” would hit anyone who spent 200-240 days in active combat. But while terms like “battle fatigue” and “thousand-yard stare” entered the popular lexicon, the main solution was to improve rotation into and out of active combat
PTSD as a recognized mental illness that is understood to require psychiatric treatment didn’t really happen until after the Vietnam War.