In World War I, the men who had the least fear of the effects of gas warfare were the gas officers who understood their subject right down to the last detail of the decontamination process and the formula for dichlorethylsulphide (mustard gas). The man to whom the dangers of submarine warfare seem least fearsome is the submariner. Of all hands along the battle line, the first aid man has the greatest calm and confidence in the face of fire, largely because he has seen the miracles worked by modern medicine in the restoring of grievously wounded men. The general or the admiral who is most familiar with the mettle of his subordinate commands will also have the most relaxed mind under battle pressure. This leads to a point, which it is better to state here than anywhere else. In all military instruction pertaining to the weapons and techniques of war, the basis of sound indoctrination is the teaching that weapons when rightly used will invariably produce victory, and preventive measures, when promptly and thoroughly taken, will invariably conserve the operational integrity of the defense. It is wrong, _dead wrong_, to start, or carry along, on the opposite track, and try to persuade men to do the right thing, by dwelling on the awful consequence of doing the wrong thing. Confidence, not fear, is the keynote of a strong and convictive doctrine. In war, in the absence of information, man's natural promptings alternate between unreasoning fears that the worst is likely to happen, and the wishful thought that all danger is remote. Either impulse is a barrier to the growth of that condition of alert confidence which comes to men when they have a realization of their own strength and a reasonably clear concept of the general situation. Man is a peculiar animal. He is no more prone to think about himself as the central figure amid general disaster than he is to dwell morbidly upon thoughts of his own death. Left in the dark, he will get a certain comfort out of that darkness, at the same time that it clouds his mind and freezes his action. Disturbed by bad dreams about what might happen, he nonetheless will not plan an effective use of his own resources against that which is very likely to happen. Only when he is given a clear view of the horizon, and is made animated by the general purpose in all that moves around him, does he understand the direction in which he should march, and taking hold, begin to do the required thing.