I understand, at least in part.
While I was never in the military, (missed the draft by about 6 weeks) many of my buddies did the Viet Nam shuffle. Several came back with DSS; (now called PTSD) and hearing a jackhammer or a car backfiring would put them back in the jungle with snipers gunning for them. They described the search and destroy missions well enough that I got it, at least on an intellectual level. (certainly not the emotional or experiential level)
Which is why I said to be wary of that.