Chemical warfare

The use of toxic gas in the World War dates from April 22, 1915, when the Germans launched the first cylinder attack, employing chlorine, a common and well known gas. Judging from the later experience of the Allies in perfecting this form of attack, it is probable that plans for this attack had been under way for months before it was launched. The suggestion that poisonous gases be used in warfare has been laid upon Prof. Nernst of the University of Berlin (Auld, “Gas and Flame,” page 15), while the actual field operations were said to have been under the direction of Prof. Haber of the Kaiser Wilhelm Physical Chemical Institute of Berlin. Some writers have felt that the question of preparation had been a matter of years rather than of months, and refer to the work on industrial gases as a proof of their statement. The fact that the gas attack was not more successful, that the results to be obtained were not more appreciated, and that better preparation against retaliation had not been made, argues against this idea of a long period of preparation, except possibly in a very desultory way. That such was the case is most fortunate for the allied cause, for had the German high command known the real situation at the close of the first gas attack, or had that attack been more severe, the outcome of the war of 1914 would have been very different, and the end very much earlier.

First Gas Attack

The first suggestion of a gas attack came to the British Army through the story of a German deserter. He stated that the German Army was planning to poison their enemy with a cloud of gas, and that the cylinders had already been installed in the trenches. No one listened to the story, because, first of all, the whole procedure seemed so impossible and also because, in spite of the numerous examples of German barbarity, the English did not believe the Germans capable of such a violation of the Hague rules of warfare. The story appeared in the summary of information from headquarters (“Comic Cuts”) and as Auld says “was passed for information for what it is worth.” But the story was true, and on the afternoon of the 22nd of April, all the conditions being ideal, the beginning of “gas warfare” was launched. Details of that first gas attack will always be meager, for the simple reason that the men who could have told about it all lie in Flanders field where the poppies grow.

The place selected was in the northeast part of the Ypres salient, at that part of the line where the French and British lines met, running southward from where the trenches left the canal near Boesinghe. The French right was held by the —— Regiment of Turcos, while on the British left were the Canadians. Auld describes the attack as follows:

“Try to imagine the feelings and the condition of the colored troops as they saw the vast cloud of greenish-yellow gas spring out of the ground and slowly move down wind towards them, the vapor clinging to the earth, seeking out every hole and hollow and filling the trenches and shell holes as it came. First wonder, then fear; then, as the first, fringes of the cloud enveloped them and left them choking and agonized in the fight for breath—panic. Those who could move broke and ran, trying, generally in vain, to outstrip the cloud which followed inexorably after them.”

It is only to be expected that the first feeling connected with gas warfare was one of horror. That side of it is very thrillingly described by Rev. O. S. Watkins in the Methodist Recorder (London). After describing the bombardment of the City of Ypres from April 20th to 22nd he relates that in the midst of the uproar came the poison gas!

It must be said here, however, that this was true only because the French had no protection against the gas. Indeed, it is far from being the most horrible form of warfare, provided both sides are prepared defensively and offensively. Medical records show that out of every 100 Americans gassed less than two died, and as far as records of four years show, very few are permanently injured. Out of every 100 American casualties from all forms of warfare other than gas more than 25 per cent died, while from 2 to 5 per cent more are maimed, blinded or disfigured for life. Various forms of gas, as will be shown in the following pages, make life miserable or vision impossible to those without a mask. Yet they do not kill.

Thus instead of gas warfare being the most horrible, it is the most humane where both sides are prepared for it, while against savage or unprepared peoples it can be made so humane that but very few casualties will result.

The development of methods of defense against gas will be discussed in a later chapter. It will suffice to say here that, in response to an appeal from Lord Kitchener, a temporary protection was quickly furnished the men. This was known as the “Black Veiling” respirator, and consisted of a cotton pad soaked in ordinary washing soda solution, and later, in a mixture of washing soda and “hypo,” to which was added a little glycerine. These furnished a fair degree of protection to the men against chlorine, the only gas used in the early attacks.

Phosgene Introduced

The use of chlorine alone continued until the introduction on December 19, 1915, of a mixture of phosgene with the chlorine. This mixture offered many advantages over the use of chlorine alone (see Chapter VI).

The Allies were able, through warning of the impending use of phosgene, to furnish a means of protection against it. It was at this time that the P and the PH helmets were devised, the cotton filling being impregnated with sodium phenolate and later with a mixture of sodium phenolate and hexamethylenetetramine. This helmet was used until the Standard Box Respirator was developed by the late Lt. Col. Harrison.

Allies Adopt Gas

For a week or two the Allies were very hesitant about adopting gas warfare. However, when the repeated use of gas by the Germans made it evident that, in spite of what the Hague had to say about the matter, gas was to be a part, and as later developments showed, a very important part of modern warfare, they realized there was no choice on their part and that they had to retaliate in like manner. This decision was reached in May of 1915. It was followed by the organization of a Gas Service and intensive work on the part of chemists, engineers and physiologists. It was September 25, 1915, however, before the English were in a position to render a gas attack. From then on the Service grew in numbers and in importance, whether viewed from the standpoint of research, production, or field operations.

The Allies of course adopted not only chlorine but phosgene as well, since both were cheap, easy of preparation and effective. They felt during the early part of the War that they should adopt a substance that would kill instantly, and not one that would cause men to suffer either during the attack or through symptoms which would develop later in a hospital. For this reason a large amount of experimental work was carried out on hydrocyanic acid, particularly by the French. Since this gas has a very low density, it was necessary to mix with it substances which would tend to keep it close to the ground during the attack. Various mixtures, all called “vincennite,” were prepared,—chloroform, arsenic trichloride and stannic chloride being used in varying proportions with the acid. It was some time before it was definitely learned that these mixtures were far from being successful, both from the standpoint of stability and of poisonous properties. While the French actually used these mixtures in constantly decreasing quantities on the field for a long time, they were ultimately abandoned, though not until American chemists had also carried out a large number of tests. However, following the recommendation of the American Gas Service in France in December, 1917, no vincennite was ever manufactured by the United States.

Lachrymators

Almost simultaneously with the introduction of the gas wave attacks, in which liquefied gas under pressure was liberated from cylinders, came the use of lachrymatory or tear gases. These, while not very poisonous in the concentrations used, were very effective in incapacitating men through the effects produced upon their eyes. The low concentration required (one part in ten million of some lachrymators is sufficient to make vision impossible without a mask) makes this form of gas warfare very economical as well as very effective. Even if a mask does completely protect against such compounds, their use compels an army to wear the mask indefinitely, with an expenditure of shell far short of that required if the much more deadly gases were used. Thus Fries estimates that one good lachrymatory shell will force wearing the mask over an area that would require 500 to 1000 phosgene shell of equal size to produce the same effect. While the number of actual casualties will be very much lower, the total effect considered from the standpoint of the expenditure of ammunition and of the objectives gained, will be just as valuable. So great is the harassing value of tear and irritant gases that the next war will see them used in quantities approximating that of the more poisonous gases.

The first lachrymator used was a mixture of the chlorides and bromides of toluene. Benzyl chloride and bromide are the only valuable substances in this mixture, the higher halogenated products having little or no lachrymatory value. Xylyl bromide is also effective. Chloroacetone and bromoacetone are also well known lachrymators, though they are expensive to manufacture and are none too stable. Because of this the French modified their preparation and obtained mixtures to which they gave the name “martonite.” This is a mixture of 80 per cent bromoacetone and 20 per cent chloroacetone, and can be made with nearly complete utilization of the halogen. Methyl ethyl ketone may also be used, which gives rise to the “homomartonite” of the French. During the early part of the War, when bromine was so very expensive, the English developed ethyl iodoacetate. This was used with or without the addition of alcohol. Later the French developed bromobenzyl cyanide, C₆H₅CH(Br)CN. This was probably the best lachrymator developed during the War and put into large scale manufacture, though very little of it was available on the field of battle before the War ended. Chloroacetophenone would have played an important part had the War continued.

Disadvantage of Wave Attacks

As will be discussed more fully in the chapters on “The Tactics of Gas,” the wave attacks became relatively less important in 1916 through the use of gas in artillery shell. This was the result of many factors. Cloud gas attacks, as carried out under the old conditions, required a long time for the preliminary preparations, entailed a great deal of labor under the most difficult conditions, and were dangerous of execution even when weather conditions became suitable. The difficulties may be summarized as follows:

(1) The heavy gas cylinders used required a great deal of transportation, and not only took the time of the Infantry but rendered surprise attacks difficult owing both to the time required and to the unusual activity behind the lines that became, with the development of aeroplanes, more and more readily discerned.

(2) Few gases were available for wave attacks—chlorine, phosgene and, to a less extent, chloropicrin proving to be the only ones successfully used by either the Allies or the Germans. Hydrogen sulfide, carbon monoxide and hydrocyanic acid gas were suggested and tried, but were abandoned for one reason or another.

(3) Gas cloud attacks were wholly dependent upon weather conditions. Not only were the velocity and direction of the wind highly important as regards the successful carrying of the wave over the enemy’s line, but also to prevent danger to the troops making the attack due to a possible shift of the wind, which would carry the gas back over their own line.

(4) The use of gas in artillery shell does not require especially trained troops inasmuch as gas shell are fired in the same manner as ordinary shell, and by the same gun crews. Moreover, since artillery gas shell are used generally only for ranges of a mile or more, the direction and velocity of the wind are of minor importance. Another factor which adds to the advantage of artillery shell in certain cases is the ability to land high concentrations of gas suddenly upon a distant target through employing a large number of the largest caliber guns available for firing gas.

Notwithstanding the above named disadvantages of wave attacks it was felt by the Americans from the beginning that successful gas cloud attacks were so fruitful in producing casualties and were such a strain upon those opposed to it, that they would continue. Furthermore, since artillery shell contain about 10 per cent gas, while gas cylinders may contain 50 per cent, or even more of the total weight of the cylinder, the efficiency of a cloud gas attack for at least the first mile of the enemy’s territory is far greater than that of the artillery gas attack. It was accordingly felt that the only thing necessary to make cloud gas attacks highly useful and of frequent occurrence in the future was the development of mobile methods—methods whereby the gas attack could be launched on the surface of the ground and at short notice. For these reasons gas wave attacks may be expected to continue and to eventually reach a place of very decided importance in Chemical Warfare.

Gas Shell

The firing of gas in artillery shell and in bombs has another great advantage over the wave attack just mentioned. There is a very great latitude in the choice of those gases which have a high boiling point or which, at ordinary temperatures, are solids. Mustard gas is an example of a liquid with a high boiling point, and diphenylchloroarsine an example of a gas that is ordinarily solid. For the above reason the term “gas warfare” was almost a misnomer at the close of the War, and today is true only in the sense that all the substances used are in a gaseous or finely divided condition immediately after the shell explode or at least when they reach the enemy.

Projector Attacks

Still another method of attack, developed by the British and first used by them in July, 1917, was the projector (invented by Captain Livens). This was used very successfully up to the close of the War, and though the German attempted to duplicate it, his results were never as effective. The projector consists of a steel tube of uniform cross section, with an internal diameter of about 8 inches. By using nickel steel the weight may be decreased until it is a one man load. The projector was set against a pressed steel base plate (about 16 inches in diameter) placed in a very shallow trench.

Until about the close of the war projectors were installed by digging a triangular trench deep enough to bring the muzzles of the projectors nearly level with the surface of the ground. They were then protected by sand bags or canvas covers, or camouflaged with wire netting to which colored bits of cloth were tied to simulate leaves and shadows. The projectors were fired by connecting them in series with ordinary blasting machines operated by hand from a convenient point in the rear. The digging in of the projectors in No Man’s Land or very close to it was a dangerous and laborious undertaking. The Americans early conceived the idea that projectors could be fired just as accurately by digging a shallow trench just deep enough to form a support for the base plate, and then supporting the outer ends of the projector on crossed sticks or a light frame work of boards. This idea proved entirely practical except for one condition. It was found necessary to fire with a single battery all the projectors near enough together to be disturbed by the blast from any portion of them. Inasmuch as most of the blasting machines used for firing had a capacity of only 20 to 30 projectors, it was necessary to so greatly scatter a large projector attack that the method was very little used. However, investigations were well under way at the close of the War to develop portable firing batteries that would enable the discharge of at least 100 and preferably 500 projectors at one time. By this arrangement a projector attack could be prepared and launched in two to four hours, depending upon the number of men available. This enabled the attack to be decided upon in the evening (if the weather conditions were right), and to have the attack launched before morning, thereby making it impossible for aeroplane observers, armed with cameras, to discover the preparation for the projector attack. Since the bombs used in the projector may carry as high as 30 pounds of gas (usually phosgene), some idea of the amount of destruction may be gained when it is known that the British fired nearly 2500 at one time into Lens.

Stokes’ Mortar

Another British invention is the Stokes’ gun or trench mortar. The range of this gun is about 800 to 1000 yards. It is therefore effective only where the front lines are relatively close together. The shell consists of a case containing the high explosive, smoke material or gas, fitted to a base filled with a high charge of propelling powder. The shell is simply dropped into the gun. At the bottom of the gun there is a projection or stud that strikes the primer, setting off the small charge and expelling the projectile. In order to obtain any considerable concentration of gas in a particular locality, it is necessary to fire the Stokes’ continuously (15 shots per minute being possible under battle conditions) for two to five minutes since the bomb contains only seven pounds of gas.

Superpalite

It is believed that the first gas shell contained lachrymators or tear gases. Although the use of these shell continued up to and even after the introduction of mustard gas, they gradually fell off in number—the true poison gas shell taking their place. Towards the end of 1915 Auld states that the Germans were using chloromethyl chloroformate (palite) in shell. In 1916, during the battle of the Somme, palite was replaced by superpalite (trichloromethyl chloroformate, or diphosgene) which is more toxic than palite, and about as toxic as phosgene. It has the advantage over phosgene of being much more persistent. In spite of the fact that American chemists were not able to manufacture superpalite on a large scale, or at least so successfully that it would compete in price with other war gases, the Germans used large quantities of it, alone and mixed with chloropicrin, in shell of every caliber up to and including the 15 cm. Howitzer.

Chloropicrin

The next gas to be introduced was chloropicrin, trichloronitromethane or “vomiting gas.” It has been stated that a mixture of chloropicrin (25 per cent) and chlorine (75 per cent) has been used in cloud attacks, but the high boiling point of chloropicrin (112° C.) makes its considerable use for this purpose very unlikely. The gas is moderately toxic and somewhat lachrymatory, but it was mainly used because of its peculiar property of causing vomiting when inhaled. Its value was further increased at first because it was particularly difficult to prepare a charcoal which would absorb it. Its peculiar properties are apt to cause it to be used for a long time.

Sneezing Gas

During the summer of 1917 two new and very important gases were introduced, and, as before, by the Germans. One of these was diphenylchloroarsine, “sneezing gas” or “Blue Cross.” This is a white solid which was placed in a bottle and embedded in TNT in the shell. Upon explosion of the shell the solid was atomized into very fine particles. Since the ordinary mask does not remove smoke or mists, the sneezing gas penetrates the mask and causes violent sneezing. The purpose, of course, is to compel the removal of the mask in an atmosphere of lethal gas. (The firing regulations prescribed its use with phosgene or other lethal shell.) The latest type masks protect against this dust, but as it is extraordinarily powerful, its use will continue.

Mustard Gas

The second gas was dichloroethyl sulfide, mustard gas, Yellow Cross or Yperite. Mustard gas, as it is commonly designated, is probably the most important single poisonous substance used in gas warfare. It was first used by the Germans at Ypres, July 12, 1917. The amount of this gas used is illustrated by the fact that at Nieuport more than 50,000 shell were fired in one night, some of which contained nearly three gallons of the liquid.

Mustard gas is a high boiling and very persistent material, which is characterized by its vesicant (skin blistering) action. Men who come in contact with it, either in the form of fine splashes of the liquid or in the form of vapor, suffer severe blistering of the skin. The burns appear from four to twelve hours after exposure and heal very slowly. Ordinary clothing is no protection against either the vapor or the liquid. Other effects will be considered in Chapter IX.

Since then there has been no important advance so far as new gases are concerned. Various arsenic derivatives were prepared in the laboratory and tested on a small scale. The Germans did actually introduce ethyldichloroarsine and the Americans were considering methyldichloroarsine. Attempts were made to improve upon mustard gas but they were not successful.

Lewisite

It is rather a peculiar fact that so few new chemical compounds were used as war gases. Practically all the substances were well known to the organic chemist long before the World War. One of the most interesting and valuable of the compounds which would have found extensive use had the War continued, is an arsenic compound called Lewisite from its discoverer, Capt. W. Lee Lewis, of Northwestern University. The chemistry of this compound is discussed in Chapter X. Because of the early recognized value of this compound, very careful secrecy was maintained as to all details of the method of preparation and its properties. As a result, strange stories were circulated about its deadly powers. Characteristic of these was the story that appeared in the New York Times early in 1919. Now that the English have published the chemical and pharmacological properties, we can say that, although Lewisite was never proven on the battle field, laboratory tests indicate that we have here a very powerful agent. Not only is it a vesicant of about the same order of mustard gas, but the arsenical penetrates the skin of an animal, and three drops, placed on the abdomen of a mouse, are sufficient to kill within two to three hours. It is also a powerful respiratory irritant and causes violent sneezing. Its possible use in aeroplane bombs has led General Fries to apply the term “The Dew of Death” to its use in this way.

Camouflage Gases

Considerable effort was spent on the question of camouflage gases. This involved two lines of research:

(1) To prevent the recognition of a gas when actually present on the field, by masking its odor.

TABLE I

Chemical Warfare Gases

TABLE I—Continued

(2) To simulate the presence of a toxic gas. This may be done either by using a substance whose odor in the field strongly suggests that of the gas in question, or by so thoroughly associating a totally different odor with a particular “gas” in normal use that, when used alone, it still seems to imply the presence of that gas. This use of imitation gas would thus be of service in economizing the use of actual “gas” or in the preparation of surprise attacks.

While there was some success with this kind of “gas,” very few such attacks were really carried out, and these were in connection with projector attacks.

Gases Used

Table I gives a list of all the gases used by the various armies, the nation which used them, the effect produced and the means of projection used.

Table II gives the properties of the more important war cases (compiled by Major R. E. Wilson, C. W. S.).

The gases used by the Germans may also be classified by the names of the shell in which they were used. Table III gives such a classification.

Markings for American Shell

In selecting markings for American chemical shell, red bands were used to denote persistency, white bands to denote non-persistency and lethal properties, yellow bands to denote smoke, and purple bands to denote incendiary action. The number of bands indicates the relative strength of the property indicated; thus, three red bands denote a gas more persistent than one red band.

The following shell markings were actually used:

TABLE II

Physical Constants of Important War Gases

TABLE III

German Shell