Military leaders know a secret: The vast majority of people are overwhelmingly reluctant to take a human life

by Lt. Col. Dave Grossman
Aug. 08, 2007

During World War II, U.S. Army Brigadier General S.L.A. Marshall asked average soldiers how they conducted themselves in battle. Before that, it had always been assumed that the average soldier would kill in combat simply because his country and his leaders had told him to do so, and because it might be essential to defend his own life and the lives of his friends. Marshall’s singularly unexpected discovery was that, of every hundred men along the line of fire during the combat period, an average of only 15 to 20 “would take any part with their weapons.” This was consistently true, “whether the action was spread over a day, or two days, or three.”

Marshall was a U.S. Army historian in the Pacific theater during World War II and later became the official U.S. historian of the European theater of operations. He had a team of historians working for him, and they based their findings on individual and mass interviews with thousands of soldiers in more than 400 infantry companies immediately after they had been in close combat with German or Japanese troops. The results were consistently the same: Only 15 to 20 percent of the American riflemen in combat during World War II would fire at the enemy. Those who would not fire did not run or hide—in many cases they were willing to risk greater danger to rescue comrades, get ammunition, or run messages. They simply would not fire their weapons at the enemy, even when faced with repeated waves of banzai charges.

Why did these men fail to fire? As a historian, psychologist, and soldier, I examined this question and studied the process of killing in combat. I have realized that there was one major factor missing from the common understanding of this process, a factor that answers this question and more: the simple and demonstrable fact that there is, within most men and women, an intense resistance to killing other people. A resistance so strong that, in many circumstances, soldiers on the battlefield will die before they can overcome it.

Indeed, the study of killing by military scientists, historians, and psychologists gives us good reason to feel optimistic about human nature, for it reveals that almost all of us are overwhelmingly reluctant to kill a member of our own species, under just about any circumstance. Yet this understanding has also propelled armies to develop sophisticated methods for overcoming our innate aversion to killing, and, as a result, we have seen a sharp increase in the magnitude and frequency of post-traumatic response among combat veterans. Because human beings are astonishingly resilient, most soldiers who return from war will be fine. But some will need help coping with memories of violence. When those soldiers return from war—especially an unpopular one like Iraq—society faces formidable moral and mental health challenges in caring for and re-integrating its veterans.

Resistance to killing

S.L.A. Marshall’s methodology has been criticized, but his findings have been corroborated by many other studies. Indeed, data indicate that soldiers throughout military history have demonstrated a strong resistance to killing other people.

When 19th-century French officer and military theorist Ardant du Picq distributed a questionnaire to French officers in the 1860s, he became one of the first people to document the common tendency of soldiers to fire harmlessly into the air simply for the sake of firing. One officer’s response stated quite frankly that “a good many soldiers fired into the air at long distances,” while another observed that “a certain number of our soldiers fired almost in the air, without aiming, seeming to want to stun themselves.”

Missing the target does not necessarily involve firing high, and two decades on army rifle ranges have taught me that a soldier must fire unusually high for it to be obvious to an observer. In other words, the intentional miss can be a very subtle form of disobedience. When faced with living, breathing opponents instead of a target, a significant majority of the soldiers revert to a posturing mode in which they fire over the enemy’s heads.

A 1986 study by the British Defense Operational Analysis Establishment’s field studies division examined the killing effectiveness of military units in more than 100 19th- and 20th-century battles. They compared the data from these units with hit rates from simulated battles using pulsed laser weapons.

The analysis was designed (among other things) to determine if Marshall’s non-firer figures were consistent with other, earlier wars. When researchers compared historical combat performances against the performance of these test subjects (who were using simulated weapons and could neither inflict nor receive actual harm from the “enemy”), they discovered that the killing potential in these circumstances was much greater than the actual historical casualty rates.

Battlefield fear alone cannot explain such a consistent discrepancy. The researchers’ conclusions openly supported Marshall’s findings, pointing to “unwillingness to take part [in combat] as the main factor” that kept the actual historical killing rates significantly below the laser trial levels.

Thus the evidence shows that the vast majority of combatants throughout history, at the moment of truth when they could and should kill the enemy, have found themselves to be “conscientious objectors”—yet there seems to be a conspiracy of silence on this subject. In his book War on the Mind, Peter Watson observes that Marshall’s findings have been largely ignored by academia and the fields of psychiatry and psychology.

But they were very much taken to heart by the U.S. Army, and a number of training measures were instituted as a result of Marshall’s suggestions. According to studies by the U.S. military, these changes resulted in a firing rate of 55 percent in Korea and 90 to 95 percent in Vietnam. Some modern soldiers use the disparity between the firing rates of World War II and Vietnam to claim that S.L.A. Marshall had to be wrong, for the average military leader has a hard time believing that any significant body of his soldiers will not do its job in combat. But these doubters don’t give sufficient credit to the revolutionary corrective measures and training methods introduced over the past half century.

Manufactured contempt

Since World War II, a new era has quietly dawned in modern warfare: an era of psychological warfare, conducted not upon the enemy, but upon one’s own troops. The triad of methods used to enable men to overcome their innate resistance to killing includes desensitization, classical and operant conditioning, and denial defense mechanisms.

Authors such as Gwynne Dyer and Richard Holmes have traced the development of boot-camp glorification of killing. They’ve found it was almost unheard of in World War I, rare in World War II, increasingly present in Korea, and thoroughly institutionalized in Vietnam. “The language used in [marine training camp] Parris Island to describe the joys of killing people,” writes Dyer, helps “desensitize [marines] to the suffering of an ‘enemy,’ and at the same time they are being indoctrinated in the most explicit fashion (as previous generations were not) with the notion that their purpose is not just to be brave or to fight well; it is to kill people.”

But desensitization by itself is probably not sufficient to overcome the average individual’s deep-seated resistance to killing. Indeed, this desensitization process is almost a smoke screen for conditioning, which is the most important aspect of modern training. Instead of lying prone on a grassy field calmly shooting at a bull’s-eye target, for example, the modern soldier spends many hours standing in a foxhole, with full combat equipment draped about his body. At periodic intervals one or two man-shaped targets will pop up in front of him, and the soldier must shoot the target.

In addition to traditional marksmanship, soldiers are learning to shoot reflexively and instantly, while mimicking the act of killing. In behavioral terms, the man shape popping up in the soldier’s field of fire is the “conditioned stimulus.” On special occasions, even more realistic and complex targets are used, many of them filled with red paint or catsup, which provide instant and positive reinforcement when the target is hit. In this and other training exercises, every aspect of killing on the battlefield is rehearsed, visualized, and conditioned.

By the time a soldier does kill in combat, he has rehearsed the process so many times that he is able to, at one level, deny to himself that he is actually killing another human being. One British veteran of the Falklands, trained in the modern method, told Holmes that he “thought of the enemy as nothing more or less than Figure II [man-shaped] targets.”

There is “a natural disinclination to pull the trigger… when your weapon is pointed at a human,” says Bill Jordan, a career U.S. Border Patrol officer and veteran of many gunfights. “To aid in overcoming this resistance it is helpful if you can will yourself to think of your opponent as a mere target and not as a human being. In this connection you should go further and pick a spot on your target. This will allow better concentration and further remove the human element from your thinking.”

Jordan calls this process “manufactured contempt.”

The hidden cost of killing

The success of this conditioning and desensitization is obvious and undeniable. In many circumstances highly trained modern soldiers have fought poorly trained guerilla forces, and the tendency of poorly prepared forces to instinctively engage in posturing mechanisms (such as firing high) has given significant advantage to the more highly trained force. We can see the discrepancy in dozens of modern conflicts, including in Somalia, where 18 trapped U.S. troops killed an estimated 364 Somali fighters, and in Iraq, where small numbers of U.S. troops have inflicted terrible losses on insurgents. Though we might be quick to credit technology for American deadliness, keep in mind that the lopsided casualty rates apply even in situations of close, small arms combat, where the technological gap between opposing forces is not a decisive factor.

The ability to increase the firing rate, though, comes with a hidden cost. Severe psychological trauma becomes a distinct possibility when military training overrides safeguards against killing: In a war when 95 percent of soldiers fired their weapons at the enemy, it should come as no surprise that between 18 and 54 percent of the 2.8 million military personnel who served in Vietnam suffer from post-traumatic stress disorder—far higher than in previous wars.

It’s important to note that, contrary to stereotype, numerous studies have demonstrated that there is not any distinguishable threat of violence to society from returning veterans. Statistically there is no greater a population of violent criminals among veterans than there is among non-veterans. What the epidemic of PTSD among Vietnam vets has caused is a significant increase in suicides, drug use, alcoholism, and divorce.

In 1988, a major study by Jeanne and Steven Stellman at Columbia University examined the relationship between PTSD manifestations and a soldier’s involvement in the killing process. This study of 6,810 randomly selected veterans is the first in which combat levels were quantified. Stellman and Stellman found that the victims of PTSD are almost solely veterans who participated in high-intensity combat situations. These veterans suffer far higher incidence of divorce, marital problems, tranquilizer use, alcoholism, joblessness, heart disease, and ulcers. As far as PTSD symptoms are concerned, soldiers who were in noncombat situations in Vietnam were found to be statistically indistinguishable from those who spent their entire enlistment in the U.S.

During the Vietnam era millions of American adolescents were conditioned to engage in an act against which they had a powerful resistance. This conditioning is a necessary part of allowing a soldier to succeed and survive in the environment where society has placed him. If we accept that we need an army, then we must accept that it has to be as capable of surviving as we can make it. But if society prepares a soldier to overcome his resistance to killing and places him in an environment in which he will kill, then that society has an obligation to deal forthrightly, intelligently, and morally with the psychological repercussions upon the soldier and the society. Largely through an ignorance of the processes and implications involved, this did not happen for Vietnam veterans—a mistake we risk making again as the war in Iraq becomes increasingly deadly and unpopular.

The resensitization of America

Today I am on the road, almost 300 days a year, speaking to numerous military organizations going in and out of the combat zone. I explain to them the two dangers that they must guard against. One danger is the “Macho Man” mentality that can cause a soldier to refuse to accept vital mental health services. But the other danger is what I call the “Pity Party.” There is a powerful tendency for human beings to respond to stress in the way that they think they should. If soldiers and their spouses, parents and others, are all convinced that the returning veteran will have PTSD, then it can create a powerful self-fulfilling prophecy.

Thus there is a careful balancing act, in which our society is morally obligated to provide state-of-the-art mental health services to returning veterans, and for the returning soldier to partake of such care if needed. But we also must remember (and even create an expectation) that most combat veterans will be okay. For those who do have a problem, we must make it clear to them that PTSD is treatable and can be curable, and when finished with it they can potentially be stronger individuals for the experience.

Most importantly, if we do want to build a world in which killing is increasingly rare, more scientists, soldiers, and others must speak up and challenge the popular myth that human beings are “natural born killers.” Popular culture has done much to perpetuate the myth of easy killing. Indeed, today many video games are actually replicating military training and conditioning kids to kill—but without “stimulus discriminators” to ensure that they only fire under authority. Even at elite intellectual levels, the natural born killer myth is too often embraced uncritically and promoted aggressively, sometimes at the service of an ideological agenda.

We may never understand the nature of the force in humankind that causes us to strongly resist killing fellow human beings, but we can be thankful for it. And although military leaders responsible for winning a war may be distressed by this force, as a species we can view it with pride. It is there, it is strong, and it gives us cause to believe that there may just be hope for human-kind after all.
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A former Army Ranger and paratrooper, Lt. Col. Dave Grossman, M.Ed., taught psychology at West Point and is formerly a professor and chair of the department of military science at Arkansas State University. He is the author of On Killing: The Psychological Cost of Learning to Kill in War and Society, which was nominated for the Pulitzer Prize for non-fiction.