Captain W.H. Livens had invented a simple oil can mortar, which had arisen from the need to find an alternative way to attack the German trenches with incendiaries, which was a much more effective weapon than any of the flamethrowers the British had. The success of these mortars led to the idea that the mortars could be used to throw gas bombs at the Germans in the same manner. When the Germans first released chlorine from 5,000 cylinders at Ypres in April 1915, against Algerian troops of the French Army, the British Army wanted a response to this new threat. By September the Army was ready to release a gas cloud of its own against the Germans at the Battle of Loos. Although these and later uses of gas clouds proved to have a limited effect against an unprepared enemy, it was realized that there were simply too many variables to guarantee success. These were mostly connected with the weather (for example, air temperature, wind speed and direction) but were also related to how far the gas had to travel and the density of cylinders in the release area. There were instances where a simple change in wind direction completely threw all planning and timetables into disarray.

Livens knew that if gas was to be effective it had to be delivered in higher densities than could be achieved with gas clouds. In addition, greater control over the gas was essential. Although both artillery shells and mortar bombs were adapted to carry gas, the effect was still limited and measures could be taken by the enemy to minimize the number of casualties. Shells and bombs could neither carry a big enough payload nor produce a high concentration in one place. It occurred to Livens that by adapting his oil can mortar bombs to carry gas instead of flammable liquid it might be possible to lay down a very dense, localized cloud of gas, especially if a large number of mortars were fired simultaneously. He conducted some experiments which showed that the idea was not only sound but potentially even more destructive than his cans of petrol.

The gas projector was first used operationally in the capture of Thiepval in September 1916, followed by a repeat performance during the capture of Beaumont Hamel in November. These were not full-scale projector operations, merely trials to prove the concept. The proof was very convincing and General Sir Hubert Gough in command of the Fifth Army and his Chief of Staff General Neill Malcolm gave Livens all the cooperation he needed to develop the weapon in the field while keeping it secret from the Germans. Both recognized the potential of the weapon and arranged for the projector to be used only against positions that would be immediately taken by the infantry. This ensured that no information about the new weapon could be passed back to the German rear. Indeed, so successful were these precautions that the Germans were completely in the dark about the projector until well into 1917 and even then they did not know how the weapon worked.

Some of the reports that the Germans did manage to write were captured before they could be sent back to the German divisional staff. The reports assumed the attacks to be gas clouds released in the usual way but of far higher density. During the Thiepval attack about 1,100 lb of gas was fired at a frontage of only 80 yd and this formed a ‘gas lake’ that flooded the cellars of the ruined Thiepval Chateau, occupied by the German commander of the Thiepval garrison. He, along with at least 130 other German soldiers, were killed by the gas. At Serre, 200 Germans were killed and the German commander reported that the attack was ‘of a new kind, of great intensity, delivered without warning’ and was desperate to know what he should do against a future attack. He received an unhelpful reply ‘to take the necessary precautions’ but died before he could do anything.

On the day after the gas attack on Beaumont Hamel, the infantry took what remained of the village. Livens discovered a deep German dugout untouched by ‘our heaviest shelling with twelve inch howitzers’, with fifteen Germans, five rats and a cat all dead. They had died in the act of trying to escape and the evidence suggested that it had happened within a matter of a few seconds. This was not because the gas was any more lethal but because of its concentration.

This dug-out was in the track of a cloud containing nearly a ton of gas, and the number of seconds in which these men were killed could be gauged almost exactly, because the three furthest from the entrance down which the gas had come, had had time to put their gas-masks on before they died, the fourth man had his mask half on, and the fifth had it to his face, the sixth out of the box, the seventh had opened the box, and completing the series, the eight[h] had his hand on the lid, while those in front were killed so quickly they had not had time even to think about their masks.

Livens likened the scene to ‘a cinematographic series of photographs of German gas-mask drill’.

The well-trained German soldier could don his gas mask in less than 6 seconds. In all likelihood, the concentration of gas was so high that the normal gas mask was ineffective. What made the scene all the more remarkable was the fact that the centre of the beaten zone (the area into which all the drums were fired) was some 300 yd away and the nearest bomb or ‘drum’ had landed 280 yd from the entrance. The main target, the deep artillery-proof dugouts used by the German garrison, revealed an even more startling picture. When these were examined, they were found to contain approximately 300 dead, all of whom had been killed by the gas. This was the reason for the comparatively light casualties suffered by the infantry when it crossed No Man’s Land to take the German positions. A similar attack on the nearby Y Ravine was equally successful. This was an astonishing vindication of the projector and gas drum projectile.

Having now established the effectiveness of the weapon (which, unlike the first oil can mortars, were made by Hartley & Sugden), Livens proceeded to improve on it. The acetylene welds of the early drums which contained the gas tended to become porous due to corrosion caused by moisture and chlorine (chlorine gas is made up of diatomic molecules of chlorine, hence the chemical formula Ch, but some chlorine atoms remain unattached and these readily dissolve in water to form hydrochloric acid). This would not have been a problem but for the fact that the drums were filled with the gas in the field and had to be stored until required for use. The filled drums had no fuse and relied on splitting open on impact. Thus, the drums were not inherently strong and there was always the danger of leaks or splits from rough handling.

Eventually, fire welding of 3/16^th in sheet was shown to be the best way to make gas-tight drums and these, like the first gas drums, were made by Stewart & Lloyd at their Coatbridge factory near Glasgow, as well as at their Birmingham factory. By the end of the war, 430,000 had been made. It is evident that the French also used the Livens Projector with drums of the same pattern and the Italians proposed to do likewise.

The projectors only had a range of 350 yd which, as the battles of the Somme developed, was quickly recognized as too short. Livens needed a more robust tube from which to project the gas drums, and discovering that ‘a certain quantity of waste Mannesmann tubing in odd lengths’ was left over from work done for the Admiralty he decided to experiment with this. (The Mannesmann process made seamless tubing from a metal bar with two eccentrically mounted rollers. The rollers simultaneously rotated the bar and forced it over a mandrel.) Livens selected 8 in diameter tubing which had to be at least 3 ft long to maintain a minimum length to calibre ratio of four to one which earlier experiments had shown to be essential for the ‘parallel portion’ of the bore if the projector was to fire a drum to a good range. Anything less than this caused the range to drop off drastically. The maximum weight of the projector had to be kept to 100 lb as this had been determined as the maximum load that could be carried without special equipment. The length and weight determined the thickness of the walls of the projector which were 3/8^th in thick. A black powder charge gave a range of 1,300 yd and was electrically ignited, the wires passing down the tube from the muzzle to the charge.

By now, the First, Third, Fourth and Fifth Armies were keen to get hold of as many of the projectors as possible. This required coordination with GHQ and General Thuillier as Director of Gas Services arranged with the Ministry of Munitions and the War Office to have as many projectors as possible manufactured in time for the forthcoming offensive in the spring of 1917. Livens attended the conference in the UK and remained in England to help deal with the technical problems that needed to be resolved. It was during this time that he perfected the drums. The projector had been transformed from an improvised device into a ‘proper’ weapon system. Throughout the whole process, Livens had not worked alone and he owed a debt of gratitude to many officers, as well as to his father, which he was only too willing to acknowledge. In fact, he made it plain that the credit for the invention should be shared equally between himself and his father. Without the support of the Director of the Trench Warfare Supply Department, the weapons would never have reached France in the numbers needed to make the impact they were about to make.

The Livens Projector was, of course, a mortar and the Livens Drum was a mortar bomb. The reason the projector was not called a mortar was logistical rather than secrecy although the term did help to obscure what the projector was. By avoiding calling the weapon a mortar meant that it was not classified as a gun. Guns came under the auspices of the Ordnance Board which would have been responsible for supplying the weapon. This would have inevitably slowed the supply process because of all the other guns which the Ordnance Board had to deal with. But if the weapon was called something else that did not suggest ‘gun’, it could be supplied to France by other means, i.e. the Trench Warfare Supply Department. The significance of all this was the speed with which Livens wanted the weapons supplied so that they could be used in the numbers necessary for them to be truly effective.

Vimy Ridge in April 1917 was the debut of the new projector. Half an hour after dawn broke, 2,000 were set up along a crescent of front above Arras and opposite Vimy Ridge. From an aircraft, Livens watched the drums burst on the German lines and the gas cloud drift over their positions. It travelled for more than 4 miles. The Germans believed that the ‘Gas Minnen’ had been propelled pneumatically or by catapults of prodigious proportions because they had heard nothing before the drums arrived. As Livens wrote later ‘A catapult which would throw a 65 Ib bomb well over a kilometre would have surprised even Archimedes’. The absence of noise was rather puzzling, however, since these projectors were far from quiet and 2,000 of them made a tremendous noise that could be heard 40 miles away over the noise of the artillery bombardment. Livens concluded that the noise was not associated with the gas drums partly because those on the receiving end tended to be dead so that there was little opportunity to communicate information with the rear. Moreover, the considerable flash of 2,000 projectors being fired simultaneously could have been mistaken for a mine being exploded. But this was pure speculation. The German casualties during the assault on Vimy Ridge were immense.

Even before Vimy Ridge, Livens had been experimenting with alternative propellants to black powder to increase the range of the projector. Newton, now a colonel and Deputy Controller of the Trench Warfare Department, provided invaluable assistance as did Colonel A.W. Crossley, Commandant of the Gas Warfare Experimental Ground at Porton Down. With the further assistance of Captain H. Goodwin, flake cordite was chosen as the propellant. However, this type of propellant needed an initial pressure of at least 1 ton per square inch for it to be burned properly. The space between the wall of the projector and the drum had to be reduced to achieve this level. It had always been a requirement that neither the tube nor the drum should be machined in any way as this would slow down production. The tolerances were consequently low. Therefore, Livens had to find a way of closing the gap that did not involve machining. He came up with a steel gas check fixed to the charge box.

The first trial with the cordite and gas check was held after Livens’s return to England after Vimy Ridge. It was successful, the range being increased to 1,800 yd. He believed that this increase ‘more than doubled the value of the weapon’. Later experiments with bombs of stronger construction showed that the range could be extended to 2,500 yd but these were not ready for use before the end of the war. With the weaker drums, the range could not be extended beyond 1,800 yd as the higher cordite charges needed to achieve the longer ranges tended to make the drums bulge which caused the projectors to burst.

In the autumn of 1917, Livens became a member of the Trench Warfare Committee. The committee took on the job of further development of the projector and several variations on the tube were developed to overcome the shortage of Mannesmann tubing. The most important of these were the wire-wound projectors and the forged projectors. The wire-wound projector was, in fact, a composite of lap-welded, ¼ in steel tubing fitted with a mild steel ‘thimble’ to strengthen the breech end and wound with ‘a double layer of flat gun steel wire’ which had a tensile strength of 90-100 tons per square inch. The Mannesmann projectors had a tensile strength of 40-50 tons per square inch whereas the ¼ in steel tubing only had a strength of 28-32 tons per square inch, but when it was wire-wound the finished projector was as strong as the Mannesmann projector and only a little heavier.

However, there were difficulties with wire-wound projectors because the gun wire was brittle and had to be protected against damage. There was also the problem of how to securely tie off the end of the wire. Moreover, the finished tube behaved differently from Mannesmann projectors. A 3/16^th in radial bulge rippled up the lap-welded tube as the gas check travelled up it although it regained its shape afterwards. Nevertheless, this was a potential hazard as the wire and the tube were of different tensile strengths and permanent ripples could be left in the tube rendering it useless. Yet, such objections were regarded as unimportant since there was little in the way of an alternative; they just had to live with it. Large numbers of the wire-wound projectors saw action in France.

The forged projector was also produced in large numbers, several thousand being used in action. A billet of steel was forged on a hydraulic shell-press exerting pressure of 1,500 tons per square inch, followed by two drawing press operations. The inside was left slightly tapered towards the base by the process. The tube was subsequently cleaned and made uniform with an appropriate tool. The end was trimmed and the excess metal was turned off the exterior to reduce thickness and weight. That was all there was to it. It was an expensive process but on the plus side the projector was superior to any other with a longer range, the slight taper seeming to be a distinct advantage.

The projector was so effective that no one was surprised when the Germans began to make copies to return the favour. There were two types and although well made they were not a patch on the British originals. More seriously for the Germans, they failed to grasp the importance of using the projectors en masse to achieve the best results. One of the types had a rifled bore which was reputed to have a very long range but when tested by Livens he could only achieve 2,800 yd with it. It was also expensive to make and could not have been produced in large quantities because of its complexity. By the end of the war, the Allies had manufactured more than 150,000 projectors and more would have been used had they been available.

Livens declined to speculate on what might have been achieved had more projectors been available along with the necessary gas-filled bombs but he cited an operation where 600 projectors had been used to indicate the ‘devastating nature’ of the weapon. The operation took place near Passchendaele in October 1917. One night, two Special Companies of Royal Engineers fired 600 projectors in two groups. The German 80th and 81st Reserve Infantry Regiments, at whom the projectors were aimed, were nearly annihilated and another regiment suffered heavy casualties. In all, 2,500 Germans were killed in the operation. One reason for the high death toll was that the Germans had been caught in the middle of a relief but that did nothing to detract from the power of the weapon.

Besides the British and the French, the Americans also used the Livens Projector. The Italians had planned to use it but the war ended before they got the chance. The weapon certainly terrified the Germans, not just because of its devastating effects, but because they never knew when an attack would occur. Many of the gas attacks carried out by the British after Vimy Ridge in 1917 were conducted with Livens Projectors. The German Army suffered such high casualties from these attacks that its soldiers were forbidden to talk about the effects.

In the Geneva Gas Protocol of the Third Geneva Convention, signed in 1925, the signatory nations agreed not to use poison gas in the future, stating “the use in war of asphyxiating, poisonous or other gases, and of all analogous liquids, materials or devices, has been justly condemned by the general opinion of the civilised world.”

Nevertheless, precautions were taken in World War II. In both Axis and Allied nations, children in school were taught to wear gas masks in case of gas attack. Italy did use poison gas against Ethiopia in 1935 and 1936, and Empire of Japan used gas against China in 1941. Germany developed the poison gases Tabun, Sarin, and Soman during the war, and, infamously, used Zyklon B in Nazi extermination camps. Neither Germany nor the Allied nations used any of their war gases in combat, despite maintaining large stockpiles and occasional calls for their use, possibly heeding warnings of awful retaliation.