Grossman's On Combat & On Killing(2009 ed)....
I would suggest LTC David Grossman's On Killing(2009) & his other book: On Combat.
He explains military structure, training, veteran issues, and the dynamics of the act of killing.
David Grossman retired from the US armed forces & started as a lower enlisted soldier. He also was jump & Ranger qualified.
His points about "personal kills" & how only approx 2% of all active duty troops can kill w/o remorse or be damaged by the combat is worth the read.
LTC Grossman also explains the fact that US Army doctrine/training does not want combat soldiers to kill, but to wound the enemy. This plan(in theory) will cause the enemy to direct troops to aid the wounded/lower morale.
Many people in the general public & some active duty soldiers(in all fields) do not clearly understand that point.
The end goal of the military is NOT to kill but to carry out missions or reach goals. Death is not always required or mandated.
PS: He also writes in On Killing that approx 50,000 rounds were expended for EKIA(enemy killed) in the entire SE Asia conflict