A man standing at “attention” by the side of his bed, surrounded by his comrades and faced by the medical officer, the military sister, and perhaps even by other members of the staff may volunteer the information that he is sleeping badly. But this imposing procession and cloud of witnesses is scarcely conducive to the production of any further evidence as to the cause of his insomnia. For of those causes even pre-war experience makes it possible to assert that their name is legion, and their character often of an exceedingly intimate and private nature. The formal visiting of patients in the wards, while adequate for the care of physical injuries (which can be subsequently attended to by trained nurses and sisters) and necessary for administrative and disciplinary purposes, is insufficient for “mental cases.” It is with this fact in mind that the military authorities have instituted special hospitals in which more detailed attention may be given to the latter class of patients. In these institutions the soldier may have private interviews with his medical officer, and the history of the trouble can be unravelled in conversation. _It is only in this way that any scientific insight into a case of mental disorder can be obtained._ A short time spent in such interviews, or even the perusal, by the uninitiated, of the papers already published in the _Lancet_, _British Medical Journal_, and elsewhere[3], will convince one of the immense complexity of these unusual mental conditions, and moreover, of the absolute necessity of obtaining and understanding the patient’s past history, before and during the war. A dozen cases sent back from the front as shell-shock may prove to possess not a single feature in common—except the fact of the shell explosion. And this, as has been pointed out, may be but the “last straw.”[4] The patient often discloses in the first interview the fact that he was displaying all his present symptoms _before_ the arrival of the particular shell which laid him out. It is now possible to attempt a brief sketch of the typical conditions which give rise to some of the chief varieties of shell-shock. Let us take a common case; that of the patient who is returned to this country, figuring in the casualty lists under the terse and businesslike military formula, “shock, shell.” For various reasons, which the reader will easily supply, we choose to present a composite picture of the history of such a soldier. Not all the conditions described here need necessarily have operated in any one case taken at random, but we shall err, if at all, on the side of understatement. The correctness of the description may be checked by a reference to the papers already mentioned.[5]