This entire line of thought seems to have begun with the American author; a combat historian who was employed by the US army: S.L.A. Marshall. He wrote a book called Men Against Fire, where Marshall claimed to have done a study to prove that 75% of the men in battle did not really even aim and fire, that most of the fighting was done by a minority. This was right after WW II and made him famous and influenced military thought.

Now there is a certain logic to what he is saying. There are veterans of air warfare that tell you that some pilots would back off from the dog fight, and some sort of half engage the enemy but not really go full out, and a smaller number would actually go full out and engage in dog fights. Sort of the same thing if you've ever been in a street fight. Or if you watch ball players get into a fight in baseball. Right? THere's usually 2 or 3 guys going all crazy and trying to kill each other, there's usually a few more who are brave enough to try to keep them apart, and the rest of the guys are milling about, push and shoving not really willing to come to blows.

So yeah I can see what he was saying...

having said that; SLA Marshall is a very questionable authority. Lots of soldiers had issues with his methods. Col. David Hackworth did a tour with Marshall in Vietnam and found him one to never let a good story get in the way of fact. Hackworth says Marshall was always getting the name and hometown of every soldier he came across because every time you mentioned someone by name, that would sell 50 more books. According to hackworth: Marshall was simply about gathering tons of information and churning that into another book and making more money.

Personally I think Marshall is overrated. However it should be pointed out that he has had influence in the modern US military because there is greater emphasis placed on how individuals react to the stress of combat to make sure they dont panic and keep firing their weapons. In WW II, these guys were trained to shoot and fight, but not really how to react to all that stress.

WHether it's true or not, I think Marshall had some insight to the problems of modern warfare but hard to say whether this is really true.

Today it is actually fairly accurate, with the advent of heavy weapons. In the First World War, artillery was responsible for 70% of deaths, so you have artillery crews(which have fewer men than an infantry or cavalry unit of approximately equal battlefield importance) inflicting more casualties. Same can be said of machine guns, mortars, air support, etc. even today.

Paraphrasing, but I'm reading Max Hastings' "Armageddon" now about the last year of WWII in Europe. He mentions that many military experts acknowledged that while you could extract the best fighting men from a group (40 out of 200 might have been the number), you still needed the others for, literally, "cannon fodder." There's quite a long section on the difference between Western armies in WWII, where "battle fatigue" and shock and the inability to pull the trigger were treated more compassionately than on the Russian or German sides, where "deserters" were just shot. So to some degree, your willingness to kill depends on who's standing behind you threatening to kill you if you don't...