I remember seeing a program that claimed this is because soldiers today are trained to kill against their natural instinct.

So traditionally only 20% of soldiers could actually kill, which would explain the low casualty rates in older battles pre-ww2.

Then after ww2 they figured out how to train soldiers to just react and kill, resulting in 6 in 10 soldiers killing.

And those who kill but wouldn't normally are much more susceptible to PTSD.

https://en.wikipedia.org/wiki/Killology

Wikipedia, so buyer beware. Seems like a controversial subject like that I can't help but think that a single edit like this changes the whole tone of the article:

https://en.wikipedia.org/w/index.php?title=Killology&diff=78...