CHAPTER X
LINES OF FUTURE DEVELOPMENT
The Element of Speculation.—It is of considerable interest to Introduce an element of speculation into our discussion of chemical warfare. In glancing at future possibilities, we can adopt one of two courses, follow up the clearly marked lines of recent development, or give the imagination play within the whole field of scientific possibility. The former course lies more within the scope of this book.
Chemical Tactics and Strategy.—Two basic military conceptions come to our assistance in attempting to characterise types of chemical warfare development. With a little explanation it is possible to place this or that method in the tactical or strategic class. Any new chemical warfare development capable, under a given system of individual protection, of successfully attacking the hitherto protected individual, may be termed strategic. The method may be aimed at a protected or hitherto immune human function, but if it overcomes protection it is then capable of effecting strategic results by its use on a sufficiently large scale. Thus we regard the first introduction of cloud gas by Germany, or their use of mustard gas, as examples of strategic chemical warfare moves. Any fundamental discovery of this sort, applicable to chemical warfare, is capable of strategic effects. Used only on a small scale, however, these possibilities may be lost and tactical advantages may alone accrue.
The tactical type of chemical warfare method involves the use of some new or old war chemical device in achieving a tactical objective which may, itself, form part of a larger scheme with strategic significance. Examples were plentiful during the recent war. We may refer to the use of smoke, of gas shell for neutralisation, or of cloud gas as preparation for a local infantry advance.
The same classification can be applied to the protective as to the offensive side of chemical warfare. The equipment of an army of millions with a gas mask has a strategic value, if it counters the large-scale use of gas by the enemy. The mere fact of this protection may serve the same purpose as a violent resistance to a huge enemy attack. It may render the attack, and, therefore, the resistance, out of the question. By permitting the individual soldier to retain the efficient use of his weapons in gas, the mask, or other form of individual protection, may render a costly counter-attack unnecessary. In this way protective methods in chemical warfare may be the determining factor in some strategic campaign or tactical activity. The distinction between tactics and strategy in chemical warfare cannot be made by grouping substances, or their methods of application to war, any more than one can say that certain infantry or artillery formations or weapons have a purely strategic or tactical function. The distinction lies rather in the magnitude and incidence of use of the chemical appliance on the battle-field, while depending on its novel nature. A new substance, possessing potential strategic value, may be wasted, and its surprise effect lost, in some local affair. This applies to the use of mustard gas by the Germans and to our own use of the Livens projector. Our armies were surprised and our plans modified by the German use of mustard gas at Ypres and Nieuport. We were not clear where this new thing was tending. Think of its strategic and psychological value had it been used on a scale and front twenty times larger. Leaving the chemical field, we can say that the first British use of the tank provided another example.
New War Chemicals.—The question of entirely new war chemicals is of general interest. The first main group of substances with which we were faced during the war contained such types as chlorine and phosgene, whose chief line of attack was directed towards the respiratory system. Specific protection rapidly developed and, once obtained, led to violent attempts to penetrate it or "break it down." In other words, the attempts to penetrate the mask by using higher concentrations of phosgene were analogous, from our point of view, to similar attempts by the use of an entirely new substance aimed again at the respiratory system. The introduction of mustard gas confirmed, what the use of lachrymators had suggested, that the most fruitful line would be found by attacking human functions hitherto immune. First the lungs, then the eyes, then the skin of the human being came under fire, so to speak. What further developments appear possible on these lines? Assuming that means are found to protect satisfactorily the respiratory system, and the eyes, what other vulnerable points can the war chemical find in the human organism? Some more specific vesicant, some modification of mustard gas, might arise, limited in attack to certain portions of the human being. The Germans were already at work on these lines.
"Camouflage" Chemicals.—It is by no means visionary to picture the loss of the sense of taste and smell by the use of some chemical. Partially successful efforts were made by both sides during the war to mask the odour of the harmful constituent of a shell filling by introducing an appropriate "camouflage" compound. Whole series of chemicals were examined from this point of view by the American field laboratory at Puteaux near Paris. The step from specific camouflage compounds to a single general type is by no means unbridgeable in theory.
An insight into work of this kind has been given by Colonel R. F. Bacon of the American Chemical Warfare Service. He says: "The gas-camouflage is of particular interest. It has been found that malodorous compounds (butyl mercaptan, dimethyl tricarbonate, etc.), are useful to mask the presence of other `gases' or to force the enemy to wear respirators when no other `gases' are present. As in the case of lachrymators, such `stink gases' must frequently be accompanied by other `gases,' in order that the enemy may never know when toxic gases are actually absent. Camouflage gases are also useful in that they save `mustard gas' and the highly lethal gases. Their value has been demonstrated in trials at Hanlon Field and also at the front." The use of such compounds has an obvious value. By removing the possibility of detecting the dangerous chemical, they enforce the permanent use of the protective appliance or encourage a fatal carelessness in the individual soldier.
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.
The New No-Man's-Land.—The recent war witnessed a rather sudden adoption of trench warfare, during a period in which the artillery strengths of both sides were relatively feeble, when compared with the later stages of the war. Accordingly, there arose very definite lines of field fortifications, and strongly held trench systems, separated from each other by a comparatively narrow No-Man's-Land, With the development of the formidable artillery strengths of belligerents, there was a tendency to form a much wider No-Man's-Land, and the front line systems were lightly held, approximating, in many cases, to an outpost line.
The discovery and mass production of a persistent lethal substance is likely to convert No-Man's-Land into a permanently infected gas zone, manned by special outposts of permanently protected troops. Combined with the development of smoke, this may render unnecessary the highly organised trench assembly systems of the recent war, used before the assault, and, with the development of the tank as a fast fighting machine, and for the transport of troops, one can obtain a glimpse of the nature of the new attack and counter-attack. A recent writer[1] has shown us the future tank carrying war into the enemy's country and destroying his nerve centres by actually reaching and paralysing the G.H.Q.s. of armies and smaller formations. Such operations will have to occur through a wide zone of the new gas and will necessitate the anti-gas tank. Indeed, one of the most important functions of the tank will be to carry the advance guard of an army beyond the infected No-Man's-Land, and such an advance will occur behind a series of smoke barrages created, in the first place, by the artillery, and, later, by the advance of tanks themselves.
[1] Tanks in the Great War, Col. J. F. C. Fuller., D.S.O.
The "Alert Gas Zone."—The development of the "gas alert" idea has definite interest for the future of chemical warfare. It is well known how the development of gas shell and surprise gas shoots by the Germans led to the necessity for "gas alert" conditions between certain times and within certain distances of the front line. The mask had to be worn in the so-called ready position, in order that swift adjustment might be possible in case of surprise attack. The summer of 1917 witnessed a great increase in gas shell activity. This was reflected in important changes in the "gas alert" regulations. In the autumn of that year all periods of readiness were abolished and replaced by a constant state of readiness. In the forward area absolute readiness was required within two miles of the front line, and special precautions were taken as far back as twelve miles. That the Germans suffered under the same restraints is witnessed by many captured documents. In particular, a divisional order taken in December, 1917, gave the gas danger zone as within fifteen kilometres of the front line, and within this region every one must carry a mask. The alert position of the mask was insisted upon within two kilometres of the front line. By July the alert zone had increased in depth in both armies. This tendency must have increased, had the war continued, for both sides were employing gas in guns of larger calibres, and weapons were being devised, such as the improved German Livens projector, which gave high concentrations at much greater distances from the front line, i.e. with greater critical ranges.
We have seen how the possible development of a persistent lethal compound may produce an infected and wide No-Man's-Land. Imposed on this, there will, no doubt, be "gas alert" conditions of great depths. How do these conceptions work out for the war of movement? It would appear that the possession of such a compound and the means of producing and using it on a very large scale could determine the stationary or open nature of warfare, if other forces were not too unequal. A new military factor emerges, the artificial, permanent, unmanned obstacle, which can be laid down at will on areas whose magnitude depends finally on manufacturing capacity. The germ of the idea appeared during the war at Kemmel and in the various mustard gas barrages formed by artillery or delayed mines used by the Germans in their great retreat. The sudden development of such barriers will be equivalent in effect to the creation of strong trench systems, but these could never result, under war conditions, in time to approach the strategic flexibility and importance of the persistent lethal infected barrier.
Gas and Aircraft.—The combination of gas and aircraft presents the possibility of attaining strategic effects by chemical means. Many rumours were afloat, towards the end of the war, regarding the use of gas by enemy aircraft, and there was apprehension amongst the civil populations, which has been reflected in numerous public utterances. Evidence on the matter is very scanty. In July, 1917, the use of gas in aeroplane bombs by the Germans was reported, but not confirmed. Further reports in August indicated the use of Blue Cross, owing to the sneezing effects which were produced on those within reach of the air bomb. In October, the evidence was more conclusive. But the German aeroplanes left no blind or dud shell, and, beyond the violent nasal and sneezing effects of Blue Cross, evidence was again absent. This report was very persistent, for, in July, 1918, there were again rumours that Blue Cross bombs had been dropped on the British near Ficheux. The Air Forces of the different armies were, perhaps, the last to feel the effects of the gas campaign, but the pilots of low-flying aeroplanes in the 1918 offensive were constantly crossing pockets of gas, and this, added to the fact that the pilots were often compelled to land in gas, led to their equipment with gas masks. A respirator of special type was taken from a German aviator in April, 1918, after the fighting at Passchendaele. But the war gave us no direct evidence of the successful use of gas and war chemicals from aircraft. This, however, is no criterion as to its eventual importance. The Allies definitely refrained from employing the combination until Germany should give them the start in what was regarded as a new atrocity. The main reason for their lack of development on these lines was probably the fact that the most suitable type of gas only developed during the later stages of the war, when it was required exceedingly urgently on the front. No really harmful persistent compound appeared before the advent of mustard gas, and the dangerous non-persistent types, such as phosgene, could not have been used with great success, owing to the fact that very considerable quantities would have been required to produce any serious effect. Mustard gas, however, which could have haunted a city for days, would not have been required in such large quantities. But its more urgent need on the front, and the fact that soon after it arrived the Germans were sending out feelers to see whether the Allies would consider the cessation of chemical warfare, were probably sufficient reasons to explain their failure to use it from aeroplanes.
Another point must be raised in connection with the use of gas from aircraft which has not yet received much attention. We must remember that the use of projectiles from aircraft over a city was a very different proposition from their use over a battle-field. One of the advantages of gas over explosives on the field of battle was its greater range of action. It produced effects at longer distances from the point of impact, but no such incentive existed for the use of gas from aeroplanes over large cities. Explosives, which might miss their objective on the field of battle, could not do so in a city. They were bound to hit something. The load of the aeroplane is always important, and the essential is to carry, weight for weight, the material which will produce the most effect. There is no doubt what this will he when the persistent lethal compound arrives, and mustard gas would probably have been superior to explosives for use by German aircraft on British cities.
Protective Development;—Individual Protection.—The question of protection against chemical attack presents some knotty problems for the future. Let us glance at the broad lines of war development in this field and forecast their future in a speculative way. Protection developed along two main lines. Individual protection covered the mask and any other protective appliance used by the individual soldier, while the term collective protection was applied to any method or appliance which afforded simultaneous protection for a number of individuals.
In general, the former represented an attempt to purify the poisoned air actually inspired by the soldier, whereas the latter was an attempt to purify the atmosphere of a locality or to prevent its initial poisoning. How far can the individual form of protection develop to meet the possibilities of the chemical attack? It certainly seems to have countered satisfactorily all the war attacks upon the respiratory system, although, as we have pointed out, the Germans might have failed, had we been sufficiently prompt in introducing our arsenic compounds. But we have forecasted the use of chemicals which may attack human functions hitherto immune. For the sake of our argument, we can divide these into two classes, those attained through the respiratory and digestive systems and those attained through contact with some other part of the body. The former can probably be satisfactorily met by developments in the mask. Even that does not appear certain, when we remember the emphasis laid by Germany upon the possibility of penetrating the mask by using a particulate cloud. The last word has certainly not been spoken in the struggle between the mask and the chemical attempting to penetrate it. But both the introduction of mustard gas and general speculative grounds justify us in concluding that attacks may materialise upon other parts of the human organism, We cannot foresee the actual point of attack and can, therefore, only view with assurance some form of protection which covers the whole body.
Collective Protection.—All parties dabbled in such a form of protection, but the French were the only ones to make a large-scale experiment on the front. It was not very successful, for the burden of these oilskin suits was intolerable. It may be that some successful form of protection for the whole body will materialise, but on general grounds we can assume that development will follow other lines. What are the possibilities? They all lie in the direction of collective protection. The individual cannot be satisfactorily protected from the new gas and remain an efficient soldier. We must, therefore, see whether it is not possible to protect numbers of men by removing them from contact with the poisoned atmosphere. A stationary form of such protection was used by all the armies, but emphasised by the French, by the creation of a large number of enormous underground chambers, some capable of holding more than a thousand men, the entries to which were carefully protected by special filtering devices to prevent the entry of the poisoned external atmosphere. On the British front these enormous dug-outs, although not absent, were largely replaced by the efficient gas-proof organisation of the smaller dugouts. The use of impregnated blankets for this purpose must be well known to any who visited the front or took part in hostilities. But you cannot imprison a whole army in this way. The value of these collective protective chambers depended on the fact that a certain number of men were always on the alert in the defensive systems outside and around the chambers, exposed to those gases against which the latter chambers were devised.
In my opinion, the further intensive development of gas warfare, such as would have accompanied, say, the doubling or quadrupling of the German factory output, would have forced us into realising the limit of this collective protection. It would have compelled us to immobilise, in these shelters, more men than was consistent with the safety of the zone in question. Undoubtedly, the future of collective protection lies in some form which will leave the soldier his combatant powers, in other words some mobile form. This has already been forecasted by Colonel Fuller in his book on Tanks in the Great War. But he passes lightly over the protection of the tank against gas. With the increase in depth of infected zones, through the increasingly lethal nature of the persistent compound, the tank will he compelled to rely on filtration methods of protection, instead of the use of compressed oxygen in a gas-tight compartment. Once committed to the use of oxygen, the only safe procedure will be to close up the tank and employ the oxygen while there is any suspicion of the presence of gas, and, under these conditions, oxygen transport would become a factor militating against the prime purpose of the tank, the transport of troops and arms. It is safe to forecast a tense struggle between chemical weapons and protective tank devices in the event of future wars.
Conclusion.—The facts which we have surveyed in early chapters, and the development foreshadowed above, form part of a much wider subject, for they are but one aspect of scientific warfare. In what main directions has science modified or revolutionised modern war? Its influence has touched practically every weapon in manufacture or design, introducing profound modifications in many cases. The sum total of such changes may be claimed to have revolutionised warfare, but the term revolution should be reserved, for some more specific scientific innovation, which threatens to change the nature of war rather than merely improve existing weapons. Modern wars have all echoed the popular cry for some new scientific principle or device to settle hostilities with one sharp stroke. This conception has been the sport of writers of fiction and others for many years. The "electric" death-dealing ray, the all-powerful gas, the deadly bacteria, and the "explosion" wave have all shared in buoying up the hopes or quickening the fears of warring peoples. Contrary to popular supposition, a decisive scientific military surprise of this nature is not likely to follow close on the heels of the discovery of a new phenomenon. It is more than eighty years since the mind of a Faraday delved so fruitfully into electrical science, yet the oft prophesied large scale direct use of high voltage electricity, or some other form in war has not materialised. Organic chemistry was a well-founded branch of science early in the nineteenth century, and flourishing industries, fostered by it, were in existence thirty years ago, yet it was not until the early twentieth century, and the recent war, that we witnessed the rapid growth of organic chemical warfare, which, I claim, was as revolutionary as any other war development. The physical sciences, have left their mark on every weapon and mechanical appliance, and the cumulative effect of these changes is indeed large, but the most revolutionary upheaval in warfare, with permanent results, came from chemistry. The flexible nature of organic chemistry must not be lost sight of. In the physical sciences, electricity, for example, years of co-ordinated world progress are required to produce an epoch-making discovery which might have critical and direct war significance. Radioactivity has shown us what undreamt-of energy is bound up in the atom, and many are the prophesies regarding the harnessing of these forces for constructive activities. At least one prominent novelist has pictured their destructive use in the radioactive bomb. But the use of this wonderful store of energy for peace and war can only result from years of costly and voluminous research, and we have no idea of the difficulties involved in production, without which any invention, however telling and revolutionary, has no incidence on war. But in organic chemistry a single worker, following up some rare family of compounds, may stumble upon a substance pot far removed chemically from related compounds yet infinitely more potent for war. Mustard gas, or B:B dichlordiethylsulphide, is a member of a group of compounds differing only slightly in chemical structure the one from the other. Yet its nearest chemical relative is comparatively harmless. The persistent lethal compound which will vastly change the nature of warfare will probably be but a slight chemical modification of some harmless substance, Thus, by comparison with other branches of science as the handmaids of war, organic chemistry is sympathetic, flexible, and theoretically capable of yielding revolutionary discoveries in a relatively short time. We can only base such speculations on general grounds. Circumstances may disprove our contention over a short historical period, but it will be borne out in the long run. This is not the only reason, however, for the unique war importance of organic chemicals. It so happens that many of them are essential to our daily life, as dyes, drugs, photographic and other synthetic products. Industries, therefore, have arisen for their manufacture. And this is not all. Organic chemical factories have proved to be not only arsenals in disguise but endowed with the flexibility of their parent, the science itself. The factories and plants ignore the war significance of the problems put to them. They can develop the production of practically any chemical which research can produce. The will of man can thus silently and swiftly convert the dye factory into an arsenal.
These inherent possibilities of organic chemistry, flexibility in research and production, make chemical warfare the most important war problem in the future reconstruction of the world.