Some years ago the nations of the world gathered at the city of The Hague, in Holland, to see what could be done to put an end to war. They did not accomplish much in that direction, but they did draw up certain rules of warfare which they agreed to abide by. There were some practices which were considered too horrible for any civilized nation to indulge in. Among these was the use of poisonous gases, and Germany was one of the nations that took a solemn pledge not to use gas in war.

Eighteen years later the German Army had dug itself into a line of trenches reaching from the English Channel to Switzerland, and facing them in another line of trenches were the armies of France and England, determined to hold back the invaders. Neither side could make an advance without frightful loss of life. But a German scientist came forth with a scheme for breaking the dead-lock. This was Professor Nernst, the inventor of a well-known electric lamp and a man who had always violently hated the British. His plan was to drown out the British with a flood of poisonous gas. To be sure, there was the pledge taken at The Hague Conference, but why should that stand in Germany's way? What cared the Germans for promises now? Already they had broken a pledge in their violation of Belgium. Already they had rained explosives from the sky on unfortified British cities (thus violating another pledge of The Hague Conference); already they had determined to war on defenseless merchantmen. To them promises meant nothing, if such promises interfered with the success of German arms. They led the world in the field of chemistry; why, they reasoned, shouldn't they make use of this advantage?

POURING GAS LIKE WATER

It was really a new mode of warfare that the Germans were about to launch and it called for much study. In the first place, they had to decide what sort of gas to use. It must be a gas that could be obtained in large quantities. It must be a very poisonous gas, that would act quickly on the enemy; it must be easily compressed and liquefied so that it could be carried in containers that were not too bulky; it must vaporize when the pressure was released; and it must be heavier than air, so that it would not be diluted by the atmosphere but would hug the ground. You can pour gas just as you pour water, if it is heavier than air. A heavy gas will stay in the bottom of an unstoppered bottle and can be poured from one bottle into another like water. If the gas is colored, you can see it flowing just as if it were a liquid. On the other hand, a gas which is much lighter than air can also be kept in unstoppered bottles if the bottles are turned upside down, and the gas can be poured from one bottle into another; but it flows up instead of down.

Chlorine gas was selected because it seemed to meet all requirements. For the gas attack a point was chosen where the ground sloped gently toward the opposing lines, so that the gas would actually flow down hill into them. Preparations were carried out with the utmost secrecy. Just under the parapet of the trenches deep pits were dug, about a yard apart on a front of fifteen miles, or over twenty-five thousand pits. In these pits were placed the chlorine tanks, each weighing about ninety pounds. Each pit was then closed with a plank and this was covered with a quilt filled with peat moss soaked in potash, so that in case of any leakage the chlorine would be taken up by the potash and rendered harmless. Over the quilts sandbags were piled to a considerable height, to protect the tanks from shell-fragments.

Liquid chlorine will boil even in a temperature of 28 degrees below zero Fahrenheit, but in tanks it cannot boil because there is no room for it to turn into a gas. Upon release of the pressure at ordinary temperatures, the liquid boils violently and big clouds of gas are produced. If the gas were tapped off from the top of the cylinder, it would freeze on pouring out, because any liquid that turns into a gas has to draw heat from its surroundings. The greater the expansion, the more heat the gas absorbs, and in the case of the chlorine tanks, had the nozzles been set in the top of the tank they would very quickly have been crusted with frost and choked, stopping the flow.

But the Germans had anticipated this difficulty, and instead of drawing off the gas from the top of the tank, they drew off the liquid from the bottom in small leaden tubes which passed up through the liquid in the tank and were kept as warm as the surrounding liquid. In fact, it was not gas from the top of the tank, but liquid from the bottom, that was streamed out and this did not turn into gas until it had left the nozzle.

WAITING FOR THE WIND

Everything was ready for the attack on the British in April, 1915. A point had been chosen where the British lines made a juncture with the French. The Germans reckoned that a joint of this sort in the opponent's lines would be a spot of weakness. Also, they had very craftily picked out this particular spot because the French portion of the line was manned by Turcos, or Algerians, who would be likely to think there was something supernatural about a death-dealing cloud. On the left of the Africans was a division of Canadians, but the main brunt of the gas was designed to fall upon the Turcos. Several times the attack was about to be made, but was abandoned because the wind was not just right. The Germans wished to pick out a time when the breeze was blowing steadily—not so fast as to scatter the gas, but yet so fast that it would overtake men who attempted to run away from it. It was not until April 22 that conditions were ideal, and then the new mode of warfare was launched.

Just as had been expected, the Turcos were awe-struck when they saw, coming out of the German trenches, volumes of greenish-yellow gas, which rolled toward them, pouring down into shell-holes and flowing over into the trenches as if it were a liquid. They were seized with superstitious fear, particularly when the gas overcame numbers of them, stifling them and leaving them gasping for breath. Immediately there was a panic and they raced back, striving to out-speed the pursuing cloud.

For a stretch of fifteen miles the Allied trenches were emptied, and the Germans, who followed in the wake of the gas, met with no opposition except in the sector held by the Canadians. Here, on the fringe of the gas cloud, so determined a fight was put up that the Germans faltered, and the brave Canadians held them until reinforcements arrived and the gap in the line was closed.

The Germans themselves were new at the game or they could have made a complete success of this surprise attack. Had they made the attack on a broader front, nothing could have kept them from breaking through to Calais. The valiant Canadians who struggled and fought without protection in the stifling clouds of chlorine, were almost wiped out. But many of them who were on the fringe of the cloud escaped by wetting handkerchiefs, socks, or other pieces of cloth, and wrapping them around their mouths and noses.

The world was horrified when it read of this German gas attack, but there was no time to be lost. Immediately orders went out for gas-masks, and in all parts of England, and of France as well, women were busy sewing the masks. These were very simple affairs—merely a pad of cotton soaked in washing-soda and arranged to be tied over the mouth and nose. But when the next attack came, not long after the first, the men were prepared in some measure for it, and again it failed to bring the Germans the success they had counted upon. One thing that the Germans had not counted upon was the fact that the prevailing winds in Flanders blow from west to east. During the entire summer and autumn of 1915, the winds refused to favor them, and no gas attacks were staged from June to December. This gave the British a long respite and enabled them not only to prepare better gas-masks, but also to make plans to give the Hun a dose of his own medicine.

WHEN THE WIND PLAYED A TRICK ON THE GERMANS

There were many disadvantages in the use of gas clouds, which developed as the Germans gathered experience. The gas started from their own lines in a very dense cloud, but the cloud grew thinner and thinner as it traveled toward the enemy, and lost a great deal of its strength. If the wind were higher than fifteen miles an hour, it would swirl the gas around and dissipate it before it did much harm to the opposing fighters. If the wind were light, there were other dangers. On one occasion in 1916 a cloud of gas was released upon an Irish regiment. The wind was rather fickle. It carried the gas toward the British trenches, but before reaching them the cloud hesitated, the wind veered around, and soon the gas began to pour back upon the German lines. The Germans were entirely unprepared for this boomerang attack. Many of the Huns had no gas-masks on, and those who had, found that the masks were not in proper working-order. As a result of this whim of the winds, eleven thousand Germans were killed.

While chlorine was the first gas used, it was evident that it was not the only one that could be employed. British chemists had suspected that the Germans would use phosgene, which was a much more deadly gas, and in the long interval between June and December, 1915, masks were constructed which would keep out not only the fumes of chlorine but also the more poisonous phosgene. In one of their sorties the British succeeded in capturing some valuable notes on gas attacks, belonging to a German general, which showed that the Germans were actually preparing to use phosgene. This deadly gas is more insidious in its action than chlorine. The man who inhales phosgene may not know that he is gassed. He may experience no ill effects, but hours afterward, particularly if he has exercised in the meantime, he may suddenly fall dead, owing to its paralyzing action on the heart.

FREEING THE BRITISH TRENCHES OF RATS

Phosgene was not used alone, but had to be mixed with chlorine, and the deadly combination of the two destroyed all life for miles behind the trenches. However, the British were ready for it. They had been drilled to put on their masks in a few seconds' time, on the first warning of a gas attack. When the clouds of chlorine and phosgene came over No Man's Land, they were prepared, and, except for casualties among men whose masks proved defective, the soldiers in the trenches came through with very few losses. All animal life, however, was destroyed. This was a blessing to the British Tommy, whose trenches had been overrun with rats. The British had tried every known method to get rid of these pests, and now, thanks to the Germans, their quarters were most effectively fumigated with phosgene and every rat was killed. If only the "cooties" could have been destroyed in the same way, the Germans might have been forgiven many of their offenses.

The disadvantages in the use of gas clouds became increasingly apparent. What was wanted was some method of placing the gas among the opponents in concentrated form, without wasting any of it on its way across from one line to the other. This led to the use of shell filled with materials which would produce gas. There were many advantages in these shell. They could be thrown exactly where it was desired that they should fall, without the help of the fickle winds. When the shell landed and burst, the full effect of its contents was expended upon the enemy. A gas cloud would rise over a wood, but with shell the wood could be filled with gas, which, once there, would lurk among the trees for days. Chemicals could be used in shell which could not be used in a cloud attack. The shell could be filled with a liquid, or even with a solid, because when it burst the filling would be minutely pulverized. And so German chemists were set to work devising all sorts of fiendish schemes for poisoning, choking, or merely annoying their opponents.

GAS THAT MADE ONE WEEP

One of the novel shell the Germans used was known as the "tear-gas" shell. This was filled with a liquid, the vapor of which was very irritating to the eyes. The liquid vaporized very slowly and so its effect would last a long time. However, the vapor did not permanently injure the eyes; it merely filled them with tears to such an extent that a soldier was unable to see and consequently was confused and retarded in his work. The "tear-gas" shell were marked with a "T" by the Germans and were known as "T-shell."

Another type of shell, known as the "K-shell," contained a very poisonous liquid, the object of which was to destroy the enemy quickly. The effect of this shell was felt at once, but it left no slow vapors on the ground, and so it could be followed up almost immediately by an attack. Later on, the Germans developed three types of gas shell—one known as the "Green Cross," another as the "Yellow Cross," and the third as the "Blue Cross." The Green Cross shell was filled with diphosgene, or a particularly dangerous combination of phosgene in liquid form, which would remain in pools on the ground or soak into the ground and would vaporize when it became warm. Its vapors were deadly. One had always to be on his guard against them. In the morning, when the sun warmed the earth and vapors were seen to rise from the damp soil, tests were made of the vapors to see whether it was mere water vapor or diphosgene, before men were allowed to walk through it.

These vapors were heavier than air and would flow down into a trench, filling every nook and cranny. If phosgene entered a trench by a direct hit, the liquid would remain there for days, rendering that part of the trench uninhabitable except by men in gas-masks. The infected part of the trench, however, was cut off from the rest of the trench by means of gas-locks. In other words, blankets were used to keep the gas out, and usually two blankets were hung so that a man in passing from one part of the trench to another could lift up the first blanket, pass under it, and close it carefully behind him before opening the second blanket which led into the portion of the trench that was not infected.

The Germans had all sorts of fiendish schemes for increasing the discomfort of the Allies. For instance, to some of their diphosgene shell they added a gas which caused intense vomiting. The Yellow Cross shell was another fiendish invention of the Huns. It was popularly known as "mustard gas" and was intended not to kill but merely to discomfort the enemy. The gas had a peculiar penetrating smell, something like garlic, and its fumes would burn the flesh wherever it was exposed to them, producing great blisters and sores that were most distressing. The material in the shell was a liquid which was very hard to get rid of because it would vaporize so slowly. On account of the persistence of this vapor, lasting as it did for days, these gas shell were usually not fired by the Germans on lines that they expected to attack immediately.

THE SNEEZING-SHELL

The Blue Cross shell was comparatively harmless, although very annoying. It contained a solid which was atomized by the explosion of the shell, and which, after it got into the nostrils, caused a violent sneezing. The material, however, was not poisonous and did not produce any casualties to speak of, although it was most unpleasant. A storm of Blue Cross shell could be followed almost immediately by an attack, because the effect of the shell would have been dissipated before the attackers reached the enemy who were still suffering from the irritation of their nostrils.

GAS-MASKS

As the different kinds of gas shell were developed, the gas-masks were improved to meet them. In every attack there were "duds" or unexploded shell, which the chemists of the Allies analyzed. Also, they were constantly experimenting with new gases, themselves, and often could anticipate the Germans. The Allies were better able to protect themselves against gas attacks than the Germans, because there was a scarcity of rubber in Germany for the manufacture of masks. When it was found that phosgene was going to be used, the simple cotton-wad masks had to give way to more elaborate affairs with chemicals that would neutralize this deadly gas. And later when the mustard gas was used which attacked the eyes, and the sneezing-gas that attacked the nose, it was found necessary to cover the face completely, particularly the eyes; and so helmets of rubber were constructed which were tightly fitted around the neck under the coat collar. The inhaled air was purified by passage through a box or can filled with chemicals and charcoal made of various materials, such as cocoanut shells, peach pits, horse-chestnuts, and the like. Because the Germans had no rubber to spare, they were obliged to use leather, which made their masks stiff and heavy.

GLASS THAT WILL NOT SHATTER

One of the greatest difficulties that had to be contended with was the covering of the eyes. There was danger in the use of glass, because it was liable to be cracked or broken, letting in the deadly fumes and gassing the wearer. Experiments were made with celluloid and similar materials, but the finest gas-masks produced in the war were those made for our own soldiers, in which the goggles were of glass, built up in layers, with a celluloid-like material between, which makes a tough composition that will stand up against a very hard blow. Even if it cracks, this glass will not shatter.

The glasses were apt to become coated on the inside with moisture coming from the perspiration of the face, and some means had to be provided for wiping them off. The French hit upon a clever scheme of having the inhaled air strike the glasses in a jet which would dry off the moisture and keep the glasses clear. Before this was done, the masks were provided with little sponges on the end of a finger-piece, with which the glasses could be wiped dry without taking the masks off.

But all this time, the Allies were not merely standing on the defensive. No sooner had the Germans launched their first attack than the British and French chemists began to pay back the Hun in kind. More attention was paid to the shell than the cloud attack, and soon gas shell began to rain upon the Germans. Not only were the German shell copied, but new gases were tried. Gas shell were manufactured in immense quantities.

Then America took a hand in the war and our chemists added their help, while our factories turned out steady streams of shell. If Germany wanted gas warfare, the Allies were determined that she should have it. Our chemists were not afraid to be pitted against the German chemists and the factories of the Allies were more than a match for those of the Central Powers. When the Germans first started the use of gas, apparently they counted only their own success, which they thought would be immediate and overwhelming. They soon learned that they must take what they gave. The Allies set them a pace that they could not keep up with.

When the armistice brought the war to a sudden stop, the United States alone was making each day two tons of gas for every mile of the western front. If the war had continued, the Germans would have been simply deluged. As it was, they were getting far more gas than they could possibly produce in their own factories and they had plenty of reason to regret their rash disregard of their contract at The Hague Conference. One gas we were making was of the same order as mustard gas but far more volatile, and had we had a chance to use it against the Germans they would have found it very difficult to protect themselves against its penetrating fumes.

BATTLING WITH LIQUID FIRE

Somewhat associated with gas warfare was another form of offensive which was introduced with the purpose of breaking up the dead-lock of trench warfare. A man could protect himself against gas by using a suitable mask and clothing, but what could he do against fire? It looked as if trench defenders would have to give up if attacked with fire, and so, early in the war, the Germans devised apparatus for shooting forth streams of liquid fire, and the Allies were not slow to copy the idea.

The apparatus was either fixed or portable, but it was not often that the fixed apparatus could be used to advantage, because at best the range of the flame-thrower was limited and in few places were the trenches near enough for flaming oil to be thrown across the intervening gap. For this reason portable apparatus was chiefly used, with which a man could send out a stream for from a hundred to a hundred and fifty feet. On his back he carried the oil-tank, in the upper part of which there was a charge of compressed air. A pipe led from the tank to a nozzle which the man held in his hand, using it to direct the spray.

There was some danger to the operator in handling a highly inflammable oil. The blaze might flare back and burn him, particularly when he was lighting the stream, and so a special way of setting fire to the spray had to be devised. Of course, the value of the apparatus lay in its power to shoot the stream as far as possible. The compressed air would send the stream to a good distance, but after lighting, the oil might be consumed before it reached the desired range. Some way had to be found of igniting the oil stream far from the nozzle or as near the limit of its range as possible. And so two nozzles were used, one with a small opening so that it would send out a fine jet of long range, while the main stream of oil issued from the second nozzle. The first nozzle was movable with respect to the second and the two streams could be regulated to come together at any desired distance from the operator within the range of the apparatus. The fine stream was ignited and carried the flame out to the main stream, setting fire to it near the limit of its range. In this way a flare-back was avoided and the oil blazed where the flame was needed. The same sort of double nozzle was used on the stationary apparatus and because weight was not a consideration, heavier apparatus was used which shot the stream to a greater distance. But flame-throwing apparatus had its drawbacks: there was always the danger that the tank of highly inflammable oil might be burst open by a shell or hand-grenade and its contents set on fire. The fixed apparatus was buried under bags of sand, but the man who carried flame-throwing apparatus on his back had to take his chances, not knowing at what instant the oil he carried might be set ablaze, turning him into a living, writhing, human torch. Because of this hazard, liquid fire did not play a very important part in trench warfare; to set fire to the spray at its source with a well directed hand-grenade was too easy.

THE "FIRE BROOM"

There were certain situations, however, in which liquid fire played a very important part. After a line of trenches had been captured it was difficult to clear out the enemy who lurked in dugouts and underground passages. They would not surrender, and from their hidden recesses they could pour out a deadly machine-gun fire. The only way of dislodging them was to use the "fire broom." In other words, a stream of liquid fire was poured into the dugout, burning out the men trapped in it. If there were a second exit, they would come tumbling out in a hurry. If not, they would be burned to death. After the first sweep of the "broom," if there were any survivors, there would not be any fight left in them, and they would be quick to surrender before being subjected to a second dose of fire.