Holmes has a firm understanding of the inhibiting influences of women and children in combat when he observes:
When Barbary apes wish to approach a senior male, they borrow a young animal which they carry, in order to inhibit the senior’s aggression. Some soldiers do likewise. A British infantryman watched Germans emerging from a dugout to surrender in WWI: “they were holding up photographs of their families and offering watches and other valuables in an attempt to gain mercy.”
However, in some circumstances, even this is not enough. In this instance “as the Germans came up the steps a soldier, not from our battalion, shot each one in the stomach with a burst from his Lewis gun.” This soldier, who was willing to kill helpless, surrendering Germans one by one, was probably influenced by yet another factor that enables killing on the battlefield. And that factor is the predisposition of the killer, which we will now examine in detail.
CHAPTER FIVE
World War II-era training was conducted on a grassy firing range (a known-distance, or KD, range), on which the soldier shot at a bull’s-eye target. After he fired a series of shots the target was checked, and he was then given feedback that told him where he hit.
Modern training uses what are essentially B. F. Skinner’s operant conditioning techniques to develop a firing behavior in the soldier.[27] This training comes as close to simulating actual combat conditions as possible. The soldier stands in a foxhole with full combat equipment, and man-shaped targets pop up briefly in front of him. These are the eliciting stimuli that prompt the target behavior of shooting. If the target is hit, it immediately drops, thus providing immediate feedback. Positive reinforcement is given when these hits are exchanged for marksmanship badges, which usually have some form of privilege or reward (praise, recognition, three-day passes, and so on) associated with them.
Traditional marksmanship training has been transformed into a combat simulator. Watson states that soldiers who have conducted this kind of simulator training “often report, after they have met a real life emergency, that they just carried out the correct drill and completed it before they realized that they were not in the simulator.” Vietnam veterans have repeatedly reported similar experiences. Several independent studies indicate that this powerful conditioning process has dramatically increased the firing rate of American soldiers since World War II.

Richard Holmes has noted the ineffectiveness of an army trained in traditional World War II methods as opposed to an army whose soldiers have been conditioned by modern training methods. Holmes interviewed British soldiers returning from the Falklands War and asked them if they had experienced any incidence of nonfiring similar to that observed by Marshall in World War II. The British, who had been trained by modern methods, had not seen any such thing in their soldiers, but they had definitely observed it in the Argentineans, who had received World War II-style training and whose only effective fire had come from machine guns and snipers.[28]
The value of this modern battleproofing can also be seen in the war in Rhodesia in the 1970s. The Rhodesian security force was a highly trained modern army fighting against an ill-trained band of guerrillas. Through superior tactics
The effectiveness of modern conditioning techniques that enable killing in combat is irrefutable, and their impact on the modern battlefield is enormous.
Recent Experiences: “That’s for My Brother”
Bob Fowler, F Company’s popular, tow-headed commander, had bled to death after being hit in the spleen. His orderly, who adored him, snatched up a submachine gun and unforgivably massacred a line of unarmed Japanese soldiers who had just surrendered.
The recent loss of friends and beloved leaders in combat can also enable violence on the battlefield. The deaths of friends and comrades
Our literature is full of examples, and even our law includes concepts such as temporary insanity and extenuating and mitigating circumstances. Revenge killing during a burst of rage has been a recurring theme throughout history, and it needs to be considered in the overall equation of factors that enable killing on the battlefield.
The soldier in combat is a product of his environment, and violence can beget violence. This is the nurture side of the nature-nurture question. But he is also very much influenced by his temperament, or the nature side of the nature-nurture equation, and that is a subject that we will now address in detail.
The Temperament of the “Natural Soldier”
There is such a thing as a “natural soldier”: the kind who derives his greatest satisfaction from male companionship, from excitement, and from the conquering of physical obstacles. He doesn’t want to kill people as such, but he will have no objections if it occurs within a moral framework that gives him justification — like war — and if it is the price of gaining admission to the kind of environment he craves. Whether such men are born or made, I do not know, but most of them end up in armies (and many move on again to become mercenaries, because regular army life in peacetime is too routine and boring).
But armies are not full of such men. They are so rare that they form only a modest fraction even of small professional armies, mostly congregating in the commando-type special forces. In large conscript armies they virtually disappear beneath the weight of numbers of more ordinary men. And it is these ordinary men, who do not like combat at all, that armies must persuade to kill. Until only a generation ago, they did not even realize how bad a job they were doing.