I read S.L.A. Marshall’s 1947 Men Against Fire after seeing it cited over and over again, sometimes even in conversation. The common takeaway is that most infantrymen in the Second World War didn’t really do much in terms of killing or even shooting at the enemy. Indeed Marshall does claim that, with the qualification that “didn’t shoot” isn’t the same as “worthless”, but that’s not the only point the book makes — more broadly, it’s an attempt at a systematic if ultimately somewhat anecdotal study of infantry combat, something subject even in WWII to far less quantification and contemporary study than combat in the air or at sea.
I had a devil of a time finding this because of some TV show.