Um, how would PTSD "date" an episode? The clinical term may be recent but it's not going to go away and it didn't just start - see reports of shellshock from WW1.
PTSD being such a big and publicized topic is the difference today than from past wars. The topic of ethnic cleansing actually happening wasn't even a thought until years following WW2. The politics of war were pervasive in media much more than the conditions and microscopic effects upon those that are on the frontlines (all those war movies didn't exactly paint as grim of a picture as it was though thanks to pro-war sentiment by US leadership for decades).