Functions Hitherto Immune.—In this field of chemical attack upon hitherto immune human functions, it is particularly easy to class suggestions as visionary and to be wise only after the event. But it must be borne in mind that any nation in a position to effect such a surprise would be in a commanding position. It is believed, for example, that the human being maintains his equilibrium through the proper functioning of the semi-circular canals, organs situated behind the inner ear. It does not appear possible to attain them chemically directly, but they might be reached by the absorption of some suitable chemical into the system in the very small concentrations now possible on the field of battle. We doubt whether any physiologist would go further than to say that such a mode of attack is improbable in the near future. No qualified person would class it as impossible. It has been advanced that the control of equilibrium occurs through the movement of certain hairs through a liquid within these canals. If this be so, then one would simply require to solidify or change the viscosity of this liquid. Would this be difficult? Probably not, for most of the body fluids are of that colloidal nature in which coagulation occurs in the presence of small quantities of special agents. Such a result might cause the individual to lose his equilibrium. This would prohibit all organised movement. An army thus attained would be less mobile than a colony of cripples.
Picture for a moment such a battle as the great German attack of March, 1918—millions of men urged forward from fixed positions under highly centralised control—they advance, say, two or three miles beyond this control and are largely dependent on local initiative for the attack. They then enter clouds of shell chemical and in less than fifteen minutes a fair percentage becomes incapable of advancing in a fixed direction, of obeying local orders, or of anything more than a sort of drunken movement. By this time their supporting artillery would have been identified and attained, and the whole attack reduced to almost farcical conditions. Such a compound may never develop, but who will class it as beyond the realm of eventual possibility?
Every one is acquainted with the peculiar effects produced by various anaesthetics. The emergency uses to which they are put and our personal acquaintance with them may have dulled the imagination. Think for a moment of the possibilities which they unfold. Gaseous anaesthetics, in certain concentrations, produce temporary unconsciousness, other anaesthetics, so called local, produce absolute immobility without loss of consciousness. Chloroform and ether are common forms of the first type, but they are required in such concentrations as to render their battle use impracticable. But the second type, of which stovaine, the new synthetic drug, is a good example, produces its effects in very small concentration. A few drops injected into the spinal column are sufficient to prevent all movement for a number of hours. We cannot expect to obtain the conditions of the operating table on the battle-field, but chemicals which are effective in very small quantities or concentrations may find another channel into the human system. For this reason the development of the mask, the protection of the respiratory channels, is of great importance, for it blocks the way to substances which by mere absorption might produce valuable military results.
Chemical Constitution and Physiological Action.—It is impossible to adopt a more than speculative outlook in this field. So little is known regarding the relationships between chemical constitution and physiological action and very few sound generalisations have been made. A considerable amount of scientific work occurred on these lines in various countries before the war on the connection between the chemical nature of compounds and their taste and smell, but the relationships are still obscure.
Unsolved Problems of Mustard Gas.—The use of a chemical which attacks some unexpected human function introduces many disturbing and disorganising factors. Thus the introduction of mustard gas has left us with a number of unsolved problems. By employing this substance Germany departed from her usual caution and violated one of the first principles of chemical warfare. It is unsound for any nation to introduce a new weapon, unless that nation is, itself, furnished with the means of protection against its eventual employment by the enemy. The Germans have, themselves, explained this breach of the principles of war. They were convinced that we could not retaliate with mustard gas, because we could not produce it. It was a miscalculation but based on grounds of which they were sure, having been largely instrumental in determining them through their aggressive chemical policy.
Mustard gas attacks the respiratory system and the outer skin of man. The armies were efficiently protected against the first line of attack, but they never developed efficient protection against the second. Protection of the skin of the individual soldier against mustard gas was theoretically possible in three ways. In the first place a number of chemical solutions were devised which, applied to the affected skin, would destroy the poisonous chemical. This was a bad method, and was never efficiently employed. German army orders after the French introduction of mustard gas were bristling with references to chloride of lime or bleaching powder. It was to be kept in every conceivable place where the gas was likely to penetrate. Soldiers were provided with boxes of bleach called "Gelbolin." Permanganate of potash was carried as an alternative for a brief period. A wire from the Third German Army to the War Ministry, Berlin, dated 17th July, 1918, stated: "Chloride of lime has all been issued in boxes to the troops. Reserves exhausted." One had the impression of a drowning man catching at a straw. Supply on a sufficient scale to cover most cases was practically impossible. Each soldier would have to carry the protective chemical as part of his equipment, and its proper use depended on training. There was no time to identify and assemble the thousands of affected cases for central treatment. Mustard gas penetrated thick clothing, even boots. and was often only identified hours after the damage was done. The second method which was attempted on a large scale was the protection of each soldier by special mustard-gas-proof clothing, but a man, fighting for his life on the battle-field, will not tolerate such a handicap to movement, and, although hundreds of thousands of oiled suits were prepared and were of definite use in certain special cases, for example in certain artillery formations, yet the method must be rejected as unsuitable from a military point of view. The third solution, which was tried experimentally on a large scale, was to cover soldiers going into action with a cream or paste of protective chemical. This, again, could only be applied in special cases, prior to an assault, for example, and could not be regarded as a permanent form of protection.
As we have seen, mustard gas infected whole areas for many days, owing to its great persistency. It was often necessary to cross such zones for attack or counter-attack. How was this to be effected without huge losses? It was found possible, literally by creating roads of bleach, that is, by sprinkling bleaching powder on chosen lanes through the infected area, to pass columns of troops through such areas, but this cannot be viewed as a practicable solution. Carried to its logical conclusion, it would have taxed the possibilities of supply beyond their utmost capacity. Here, then, we have a case in which it is not possible to protect a soldier by some specific appliance, and the war found us embarking on schemes of protection by the use of chemicals in quantities which threatened to carry us out of the range of possible manufacture.
A New Type of Obstacle.—Chemical warfare has introduced a new type of strategic and tactical obstacle. Mediaeval methods of war relied largely on natural and man-built barriers. Rivers, moats, forts were, and still are, to a certain extent, critical factors in war. The conceptions of a Vauban could determine the issue of a campaign. Such obstacles were only effective, however, when properly manned and armed. The Hindenburg Line and the Canal du Nord were tremendous obstacles when backed by German artillery, rifles, and machine-guns, but, without the latter, they would have been mere inconveniences for the passage of an army. The massing of a multitude of guns, used for the first time during the recent war, produced another form of temporary obstacle, but troops could be trained to, and actually did, advance through the barrage. Further, the ultimate limits of supply and the use of counter artillery introduces time and quantitative limitations to the use of the really intensive barrage. Chemical warfare, however, has introduced a method of blocking out chosen areas of the battle-field in such a way as to prevent their effective use for military defence, communications, or other purposes. It is now possible, by chemical means, to give a normal piece of country the same value as a natural obstacle, or one organised for defence by formidable engineering construction, and manned by rifles and machine-guns. This can be achieved by the use of a highly persistent dangerous gas or war chemical of which, so far, mustard gas is the most effective example. We have seen how the Germans formed defensive flanks during their March, 1918, offensive, by spraying certain areas between their fronts of attack with mustard gas. It is true that, in the quantities in which it has, so far, been used, mustard gas has not converted open areas into absolute obstacles against the movement of a determined individual, platoon, or even larger unit. But even in the quantities which have already appeared on the battle-field, it has rendered whole zones practically unusable for huge masses of men, owing to the certainty of a very high percentage of casualties. Up to the present its value has been rather as a serious factor in Staff consideration of losses than as an actual physical barrier. Many of the casualties are only incurred a few hours after contact with the gas. This may not deter a man from crossing an affected zone, but it may deter the Staffs from using that zone, when they realise that this would imply the certainty of many thousands of casualties amongst the troops. The choice is between two evils, tactical acquiescence to the enemy's plan, blocking out a certain area, or the certainty of huge casualties. A very interesting case occurred in the German attack near Mt. Kemmel in the spring of 1918, where large quantities of German mustard gas were used some distance in front of the original line of German attack. In this case, not only was it clear that the Germans would not attempt to advance beyond a limited objective (and they did not), but the development of their attack left them organising their defences behind their own mustard gas barrage.
The "Persistent Lethal" Substance.—The importance of these considerations can hardly be exaggerated when we realise that, at any time, a substance possessing the same strategic value as mustard gas, but much more violent casualty effects, may be discovered. The Germans were certainly aware of these possibilities. According to the statement of an apparently reliable prisoner of the 30th R.I.R., July, 1918, the Regimental Gas Officer stated in a lecture that, as the Allies had used a new gas, the Germans were going to employ a "White Cross" gas shell. This gas was "stronger" than any of the gases at present in use; it possessed a persistence up to eight days, and could, therefore, not be used on the front for an assault. Its persistence was favoured by damp or misty weather and by the nature of the ground. Neither the German drum nor the masks of the Allies afforded protection against it. The last important German development consisted in the use of pumice impregnated with phosgene in their Livens bombs. It was clear that the Germans were attempting to produce a gas which was not only highly lethal but persistent. Following up this idea, we can forecast the use of a chemical which will not only permit the formation of defensive flanks, or pockets, in the enemy front, or in our own defensive positions, through their influence on Staff considerations with regard to casualties, but, by replacing the relatively mild casualty effect of mustard gas by a highly and rapidly lethal effect, will render these areas not only strategically, but physically, impassable. One of the most significant possibilities in chemical warfare development is the arrival of this type of the compound, the highly lethal, highly persistent chemical.
The Critical Range.—These considerations are very interesting from the military point of view. Consider the phenomenal amount of muscular energy required to organise any captured stretch of territory against counter-attack. The type of compound we have outlined is likely to change completely the aspect of attack and counter-attack. The Somme battlefield, for example, gave the impression of a series of defensive positions organised by the one side or the other after attack or counter-attack, in order to hold small gains of ground, which were never intended to represent the final advance. Successful progress from one trench system meant building another, under the pounding of the enemy's artillery, and the deadly fire of machine-guns, exposing, in this improvised system, large numbers of troops, among which casualties constituted a continuous drain upon eventual reserves. The arrival of the highly persistent lethal compound should provide an effective substitute for this laborious constructional protection in the shape of the persistent lethal barrage. This will render immediate counter-attack and near machine-gun fire very difficult. Automatically, fewer men will be needed to hold the advanced positions. It is true that, with the next attack, "kicking off" and assembly positions will be required, for these can be much more efficiently developed behind a deep chemical barrage and will demand the exposure of fewer men where more time is available for preparation. Such conditions, however, can only occur if one, side possesses some distinct advantage with regard to surprise by, or efficient protection against, the persistent lethal compound. When both sides are equally matched in this respect, a duel will arise in which the winner will be the one who can throw the critical concentrations of chemical into a given area at the greatest range. This might be called the "critical range." Herein lies the importance of the development of such weapons as the Livens projector, and the Germans had certainly grasped an important principle, when they used our own modified weapon against us with a much greater range than our own. If we admit the possibility of a persistent lethal compound, this question of critical range assumes outstanding importance.