Have you read On Killing by David Grossman?
Yup, both “On Killing” and “On Combat”.
I try to get my hands on everything I can in this area, which seems to be surprisingly poorly covered. Kellett’s “Combat Motivation” gives a pretty good picture of the avaiable literature up to the time it was written. Stouffer’s “The American Soldier” I haven’t yet seen at a price I can afford, and I still haven’t got round to some of Bartov’s stuff.
All the best,