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Section 2.2


The Factor of Fatigue in the Neuroses of Combat

Colonel Frederick R. Hanson
Medical Corps, Army of the United States

In World War II a terminology appeared in the military services of most nations, and in most of their major divisions, that indicated a relationship between the physical strain of combat and the occurrence of psychiatric casualties in combat troops. Many of these terms, such as "exhaustion," "combat fatigue," and "operational fatigue," not only received official sanction, but also became part of the common language of the soldier. That there is a definite relationship between physical strain and combat neurosis is inescapable, but many misconceptions and controversies have arisen as to the nature of this relationship. A brief discussion of this relationship would therefore appear to be useful.

In North Africa, Sicily, Italy, and southern France it was demonstrated repeatedly by statistical means that when units remain in contact with the enemy during combat, whether moderate or heavy, defensive or offensive, there is a progressively disproportionate increase in the number of psychiatric casualties as compared to the number of wounded. This phenomenon can be demonstrated only in battalion or smaller size units, since larger units are seldom committed as a whole. Graphs of this unit reaction show that this disproportionate increase in psychiatric casualties, expressed in terms of percent of wounded, rises steadily after about 4 days in combat. This increase, results from the increasing physical strain caused by fatigue and the increasing emotional impact of the unfavorable environment on the tiring soldier. Similar graphs of units advancing against little opposition, and, therefore, suffering little emotional stress, showed no increased in psychiatric casualties, even though conditions were such is to produce extreme physical fatigue. Evaluation of these two different situations made it abundantly clear that physical fatigue did not in itself produce psychiatric casualties. It became evident that there must be a combination of the two factors, emotional stress and physical fatigue, to bring about the progressive and disproportionate increase of psychiatric casualties. From these facts and from the discussion that follows it will be evident that physical stress tends 


to act by potentiating the impact of severe emotional stress on the soldier's ability to withstand these unfavorable emotional strains.

Any medical officer who examined combat casualties on their admission to forward medical installations was impressed by the appearance of these soldiers. Usually they were unshaven, dirty, and tired. They had obviously undergone a period of severe physical strain. They walked dispiritedly from the ambulance to the receiving tent, with drooping shoulders and bowed heads. Once in the tent they sat on the benches or the ground silent and almost motionless. Their faces were expressionless, their eyes blank and unseeing, and they tended to go to sleep wherever they were. The sick, injured, lightly wounded, and psychiatric cases were usually indistinguishable on the basis of their appearance. Even casual observation made it evident that these men were fatigued to the point of exhaustion. Most important of the factors that produced this marked fatigue was lack of sleep. Under almost all combat conditions the infantryman gets too little sleep. The conditions of his existence—the almost continuous shelling, the strange night noises, flares, sentry and patrol duties, rain, snow, cold, heat, insects, and the ever present threat of the enemy—conspire to make his sleep at best intermittent and scanty. In spite of this lack of sleep he must undergo long periods of severe exertion, more often than not on a diet that is at best deficient in calories. Often the food is there for him but he either cannot carry enough of it with him, or is too frightened to eat the proper amount. Sometimes the type available has become distasteful through its monotony.

On top of all these difficulties, the weather is often unfavorable. He is assailed by rain, snow, dust storms, or tropical heat, and must operate in the desert, swamp, or mountains. The infantryman is frequently faced with the problem of existing and fighting under one or more of these unfavorable factors. In brief, he must undergo intense exertion under conditions of unfavorable weather and terrain, without the saving recuperative factor of sufficient sleep. It is equally evident that his physical state will deteriorate and his fatigue increase as long as he is in combat where he is continuously exposed also to the emotional stress of fear, which, though it varies widely in intensity, is ever present. The history of the majority of combat-precipitated psychiatric disturbances in this theater clearly demonstrated an increasing fear of combat almost directly proportional to the time spent in combat. Over the longer term of repeated periods of combat no definite physical fatigue effect was demonstrated in this theater. The case histories presented elsewhere in this symposium give strong evidence that in any given combat period a soldier is more likely to become a psychiatric casualty when he is tired. It appears probable that the mechanisms described in the following paragraph operate.


When the average soldier goes into combat he is usually rested, well fed, and able to withstand the normal emotional stresses of combat. As times goes on he becomes increasingly tired and less well nourished, and with this decrease in physical well-being there is a corresponding decrease in his ability to cope with emotional stress. Most of us are familiar with this process in a minor way in civil life in that we find minor annoyances far more irritating when we are tired. With this decreased resistance to emotional stress, the soldier may be subjected to a moderate or severe traumatic experience. His impaired defenses are overwhelmed by this experience, and he becomes psychiatric casualty. Thus physical fatigue operates by lowering the soldier's ability to withstand emotional stress. It is probable that this phenomenon of the effect of physical fatigue functions in a quantitative rather than a qualitative way. That is, the effect is a transient one and produces no lasting alteration of the personality, and when the effects of fatigue have been counteracted the ability to withstand the emotional stresses of combat returns to its former level. Thus, it has been repeatedly demonstrated that soldiers who had a marked degree of fatigue before becoming psychiatric casualties almost invariably responded rapidly to treatment and returned to effective combat duty. Not all psychiatric patients seen in the army area were fatigued, and yet many of these nonfatigued patients could be treated and returned to combat duty. Physical fatigue might have been an important factor in many cases, but its presence was not indispensable to the success of early therapy.

Another important manifestation of the fatigue effect is that it may increase the apparent severity of the neurotic reaction. Many patients were admitted to the psychiatric services of the forward medical installations with such symptoms as crying, tremor, and emotional lability, which appeared quite severe at the time of admission but often disappeared almost completely with the restoration of a normal physical state. This symptom-potentiating effect of physical fatigue must be kept constantly in mind when one treats psychiatric casualties in the forward areas. Failure to do so may result in the unnecessary evacuation of many soldiers. In April 1943 the term "exhaustion" was adopted as the standard means of labeling all types of psychiatric casualties in the forward area of this theater. This term was chosen because it was etiologically nonspecific and when read by the soldier connoted a temporary condition.

The knowledge that physical fatigue lowers the threshold of resistance to the emotional stresses of combat proved to be one of the 


powerful tools in the therapeutic armamentarium of the forward area psychiatrist. The two major factors of such therapy were brief psychotherapy and the alleviation of physical fatigue. Furthermore, incipient neurotic reactions in overfatigued soldiers were prevented from becoming disabling by simple alleviation of physical fatigue in nonmedical regimental rest centers. (See "Psychiatry at the Division Level," page 45.)


Physical fatigue increases the occurrence of psychiatric disabilities by decreasing resistance to the emotional stresses of combat. Physical fatigue does not in itself cause the neuroses of combat. The changes in resistance to the emotional stresses of combat produced by physical fatigue are of a quantitative rather than a qualitative nature and are reversible. An important part of the treatment of psychiatric patients in the forward areas is the alleviation of associated physical fatigue.