The so-called “king of the war gases” transformed the gas war. Highly effective in low concentrations, mustard gas had a slight odor and delayed action, which, coupled with its persistence and capacity to burn and blister through clothing, defied the defensive precautions of the day. Wearing a respirator could thwart its fatal effects, and spreading decontaminants—chloride of lime on guns and bleaching powder on the ground—helped, but mustard gas produced a massive number of casualties. In the first three weeks of Yellow-Cross shelling, the British incurred more casualties (14,276), and almost as many deaths (nearly 500), as they had suffered from all previous gas engagements. From July 12, 1917 to November 23, 1918, British casualty clearing stations admitted 160,970 gas casualties, 1,859 of whom died. 77% of these were victims of mustard gas.Footnote 11
All of the casualties had to be removed for treatment to the rear; the more lightly blistered with swollen eyelids, like Captain Richard Foot, might recover in a week (IWM, Foot n.d., 98); others like T. H. Holmes, gassed on August 22, 1918, found their fighting career over (IWM, Holmes n.d.). As Tim Cook asserts, the best weapons were those that “remove fighting men and leave fear and unrest among the survivors” (Cook 1999, 215): in other words, mustard gas had a psychological effect upon everyone in a gassed area. Its slight odor was difficult to detect amongst the odors of the battlefield and its delayed action caught soldiers unawares, especially those newly deployed at the front. Mustard gas penetrated former places of safety—shell craters and trenches—, demoralizing the tired and exhausted. In rear areas, too, doctors, nurses, and orderlies had to learn how to treat their patients without suffering from cross-contamination.Footnote 12
Having seen 1,400 men gassed in the Villers Bretonneux area, Rawlinson wrote to Winston Churchill, then Minister of Munitions, on April 22, 1918:
Can you give me any idea when we may expect to have available shells filled with mustard gas? I ask because we have had very severe casualties lately from this form of projectile […] The men naturally feel that the enemy has a distinct advantage over us in possessing mustard gas and the contention of our chemists that our own lethal shells are still more effective, a contention with which I do not agree, is no satisfactory answer. We feel that we are at a disadvantage in this respect and morale suffers as a consequence (NAM, Rawlinson 1918).
Chemical weapons had already become established as a weapon of harassment. In preparations for the battle of the Somme, British army commanders dispersed gas and smoke amidst the preliminary artillery bombardments at “selected places along the whole British front,” compelling the enemy “to wear his gas helmets,” induce “fatigue,” and cause casualties (TNA, WO 256/10, Haig 1916). The ensuing 110 cylinder discharges, mainly dispersing White Star gas clouds at night, harassed the enemy and caused operational degradation. Foulkes later insisted that a cylinder gas cloud was “far more searching in its effects than the cloud produced by projectiles,” since it swept over a much more extensive area, penetrating “every nook and cranny,” and tested the enemy’s defenses more extensively than any other means of discharge (LHCMA, Foulkes, 1917).
Foulkes sought to maximize these benefits by introducing the retired cylinder or beam attack in 1918. Less hazardous to the infantry, who were withdrawn from the front lines when the attacks occurred, the operations involved thousands of cylinders loaded onto flatcars, brought up by rail (or in one case by lorries and horse-drawn wagons) to rear-area positions, and then releasing the gas simultaneously by electrical detonators. Despite losing cylinders in transport accidents, and suffering delays due to lack of wind, the Special Brigade launched ten beam attacks, releasing gas from 27,000 cylinders and achieving greater concentrations of gas than in previous cylinder operations.Footnote 13
Most gas commanders, though, preferred the flexibility of gas shells, projector drums, and mortar bombs. On all sides gunners experimented with the different types of shell and variations in the volume and rate of fire to achieve surprise, inflict casualties, and neutralize enemy batteries or at least reduce the rates of artillery fire. When faced with British gas shells at the battle of Arras, a German commander emphasized the “complete protection” of the German respirators, but acknowledged that the “fighting resistance of the men suffered considerably from wearing the mask for many hours.” Even worse, horses suffered severely from gas and so the ammunition supply faltered and “the timely withdrawal of batteries could not be affected” (TNA, WO 158/294, von Below 1917).
Various forms of harassment occurred. Once able to fire projectors and 4-inch Stokes mortars in combination, the British bombarded enemy front-line strong points, combining gas with smoke and thermit. Using eleven different fillings in the Stokes mortar bombs and projector drums, the Special Brigade attacked at “all hours of the day and night, and in all wind velocities,” even dead calm (TNA, SUPP10/292, Foulkes 1918, 3). They occasionally repeated attacks from the same front after a few hours’ interval or disguised attacks by feints with smoke. All this ingenuity reflected the effectiveness of the German respirator once it received a 3-layer drum in June 1916 and further fillings in April 1918. As the Allies were unlikely to penetrate this respirator unless it was damaged or defective,Footnote 14 they tried to catch the enemy unawares, distract him, or degrade his fighting efficiency. Even a diversionary bombardment, as took place south-east of Lens in July 1917, involved the delivery of 3,564 drums of gas and 909 mortar bombs across a 3.7 km front over five nights (REM, Crowden, August 3 1917).
During March and April 1918, including Operation Michael (March 21–April 5) the Germans discharged a massive volume of gas. As early as March 9, their “150,000 to 200,000 rounds of Yellow Cross shell […] caused heavy casualties” and, on the morning of March 21, “some millions of rounds of gas shell” targeted forward posts, trenches, strong points, batteries to a depth of 4.8 km, and villages to a depth of 12.9 km. Although the Blue Cross and Green Cross shell combination failed, as the British SBR blocked the penetration of Blue Cross agents, respirators had “to be worn for many hours, thus adding greatly to the strain and fatigue, and hampering movement and communication” (Hartley 1919–20, 499). Intensive gas shell bombardments continued into April 1918, with estimates of 30,000 to 40,000 rounds poured into Armentières on the night of April 7–8, reportedly leaving the gutters running with mustard gas (ibid.; Edmonds et al. 1918, vol. 2, 163).
The SBR minimized fatalities but protection came at a price in fighting efficiency. As Captain Arthur A. Hanbury Sparrow (Royal Berkshires) observed:
We gaze at one another like goggle-eyed, imbecile frogs. The mask makes you only half a man. You can’t think. The air you breathe has been filtered of all save a few chemical substances. A man doesn’t live on what passes through the filter—he merely exists. He gets the mentality of a wide-awake vegetable (Hanbury-Sparrow 1932, 309).
German soldiers subsequently bore the brunt of such harassment when the Allies moved onto the offensive in August 1918. The Canadians employed gas shells, up to 20%, in preliminary assaults upon German batteries, command posts, assembly trenches, observation points, and lines of communication (Cook 1999, 189–90). The American Expeditionary Force (AEF) emulated French artillery tactics, both rapid intense gas bombardments at short range to catch the enemy by surprise, and longer, slower barrages to induce fatigue and lower the enemy’s physical resistance and morale. They discharged gas in support of infantry attacks, involving 25% of the ordnance delivered. They also employed Stokes mortars in groups, firing phosgene (as well as smoke and thermit) to attack machine-gun nests, weaken resistance, and inhibit counter-attacks (Heller 1984, 86, 88). As soon as the French acquired mustard-gas shells in March, and the British in September, they incorporated them into their fire-plans: over four days from September 26, 1918 onward, the British Fourth Army fired 750,000 shells at the Hindenburg Line, including some 30,000 mustard-gas shells (Lloyd 2014, 181).
Neither at the time nor subsequently has it been possible to evaluate the exact impact of these chemical attacks. Foulkes lacked evidence about the effects of over half the attacks mounted by the Special Brigade, and the remaining evidence from British observation, the testimony of prisoners and deserters, and German letters, diaries and official documents found on the battlefield related largely to the “losses of small units” (TNA, SUPP 10/292, Foulkes 1918, 3). Both Haber and Richter rightly questioned whether much of this evidence withstood scrutiny, both the value of wartime testimony by prisoners of war and deserters, and post-war evidence from incomplete medical records, including the suspicions of malingering among a disproportionate number of the American gas casualties.Footnote 15 Yet Richter, unlike Haber, accepts that gas was perceived as a valuable means of harassment (Richter 1994, 224). The steadily increasing use of poison gas by all belligerents on the Western Front, coupled with plans to use it on an even greater scale in 1919, had the war continued, underscored this perception (Palazzo 1999, 39–50; Prentiss 1937, 684).
Finally, any assessment of poison gas during the Great War has to accept that gas was only used because conventional weapons had failed to break the deadlock of the trenches. Thereafter the belligerents relied primarily upon conventional ordnance, namely 2 million tons of high explosives and 50,000 million rounds of small arms ammunition (Prentiss 1937, 656, 662). Nor did the other novel weapons—the tank and airplane—“change the face of war” as Haber alleged (Haber 1986, 270). The Germans employed only nine tanks in their spring offensive and the British used tanks in masses on only two days during the entire war. Neither Cambrai on November 20, 1917 nor Amiens on August 8, 1918 proved decisive because the British lost the vast majority of their machines (of the 414 sent into battle on August 8, only 145 were available one day later and, by August 12, a mere six machines were able to continue). As John Terraine argued: “The German empire was not going to be overthrown by six tanks, any more than by Trenchard’s ten bomber squadrons at Nancy” (Terraine 1978, 116). Although the British and French employed aircraft in unprecedented numbers in 1918, dropping 543 tons of bombs on German targets from June 6 until November 11, 1918, these aircraft had only a supportive role. Limited by meteorological conditions during the autumn, these aerial operations were not decisive in 1918 (Edmonds et al. 1947, vol. 5, 577; Terraine 1982, 274–275, 304–306).
In short, chemical weapons were only one of several novel weapons introduced during the Great War. None of these weapons proved war winners in and of themselves, and none of them broke the deadlock of the trenches. All the major belligerents experimented with new gases and means of delivery; they ensured thereby that chemical warfare evolved in scope and method and grew steadily in tonnage, albeit within a largely supportive role. For the British army, the Special Brigade discharged 87,968 cylinders and fired 196,940 projector drums as well as 177,408 Stokes mortar bombs, delivering some 5,700 tons of gas (TNA, SUPP 10/292, Foulkes 1918, 3). By 1919, the British mounted aerial gas attacks against the Bolsheviks, hardly evidence of any failure shrouding the sense of inquiry and experimentation with poison gas (TNA, WO 106/1148, Ironside 1919).
Anti-gas defenses may have been a priority throughout the war, but if the respirators saved lives, they did so at the price of operational degradation and proffered scant protection against the burning and blistering properties of mustard gas. The desperate desire of the Allies to retaliate in kind as soon as they acquired mustard gas in 1918 demonstrated their concerns about the psychological effects and the perceived operational utility of poison gas. As Hanbury-Sparrow observed:
It wasn’t so much the harm it did to the body, which was always much over-estimated in the popular imagination, as the harm it did to the mind […] this harmless-looking almost invisible stuff would lie for days on end lurking in low places waiting for the unwary. It was the Devil’s breath (Hanbury-Sparrow 1932, 309–310).
This was hardly a weapon that failed.