I was wondering if there are any accounts of PTSD like symptoms in ancient warfare, or if it is more of a "modern" war disorder. The earliest I normally hear about are things like Shell-Shock.
There are many records of PTSD during medieval warfare, and even dating back to the ancient Greeks. However, an analysis of the character of Greek-Roman warfare will show that PTSD is likely to have had a much less severe impact on an ancient Greek or Roman soldier because of his cultural upbringing. Written records of PTSD like symptoms can be seen in many cases. The play of Philioctetes shows similar behavioral patterns seen in many modern day PTSD patients. The ancient Greek historian Herodotus may have been one of the first to write about the emotional strain associated with war. In his account of the battle of Marathon in 490 BCE, the celebrated “Father of History” noted something akin to PTSD in the case of one veteran known only as Epizelus, who says "He said that a gigantic warrior, with a huge beard, which shaded all his shield, stood over against him. But the ghostly semblance passed him by, and slew the man at his side,”It’s believed the encounter brought on a case of hysterical blindness in Epizelus, a condition occasionally seen in combat survivors. Regarding Medieval soldiers, it is often a discussed topic over cultural influences. Heebøll-Holm states that the medieval men were no more as violent as the modern day man, indicating that they were just as psychologically vulnerable as current day soldiers who undergo shell shock and such. This is a thread from over a year ago that has some great information
You can get some great answers if you search this subreddit for "PTSD", this is a very common question.
Also this in the FAQ: