Sound story

Mustard Gas and the Third Battle of Ypres

Curator, Documents & Sound Section, First World War

On the night of 12 July 1917, troops of the 45th Infantry Brigade, 15th (Scottish) Division in the Ypres sector, were subjected to an intense bombardment of gas shells containing a substance not previously encountered.

As the first casualties arrived at the nearby Casualty Clearing Stations, medical officers reported the main symptoms as being severe swelling of the eyelids, reddening and blistering of the skin, sore throats and chests and vomiting of a noxious yellow fluid.

Over the next 24 hours, as ever greater numbers arrived with similar symptoms, more serious throat and chest infections began to develop and many men found themselves unable to open their eyes. The first fatalities were recorded.  

Within a few days of the attack, the substance had been identified as dichlorodiethyl sulphide. It was an oily liquid with a distinctive mustardy smell, which was released when a shell was detonated.

The liquid attacked the skin, even through clothing, and the gas vapour given off damaged the eyes, lungs and throat, restricting breathing and in the most serious cases resulting in death from broncho-pneumonia.

Unlike other gases such as chlorine and phosgene, initial exposure to mustard gas only caused minor discomfort. Many soldiers remained in contaminated areas, often without gas masks, unaware that they had even been gassed, further increasing the number of cases needing medical treatment.

  • Treatment

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    Private Walter Cook served as stretcher-bearer and medical orderly with 27th Field Ambulance, Royal Army Medical Corps and was taken to a Casualty Clearing Station after being gassed in Ypres.

    Treatment of mustard gas casualties at Casualty Clearing Stations followed a set pattern. All clothing was removed and rigorously disinfected. The patient’s body was then thoroughly washed, and blistered skin treated with bicarbonate of soda and various ointments including petroleum jelly. Cocaine, Zinc and boric eyewash and a 2% solution of bicarbonate of soda were found effective in reducing inflamed and swollen eyes. To avoid contamination, medical staff wore protective clothing and respirators.

    Between the first attack on 13 July and the 29 July, 95 men died as direct result of exposure to mustard gas. Many hundreds more were incapacitated for varying periods of time and a high percentage of casualties required hospital treatment. The most serious cases, usually those with severe burns or respiratory problems, were sent back to the UK.  

    Image: © IWM (Q 3103)

  • Disruption

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    Realizing the potential of this new weapon, and conscious that a major Allied offensive was about to be launched, the Germans made extensive use of mustard gas, often mixed in with other types of gas, in the weeks prior to the start of the Third Battle of Ypres on 31 July 1917. Not only did it kill and disable significant numbers of men, the slow evaporation rate of the liquid meant that it could linger on the ground and in water for several weeks, contaminating large areas of terrain that were soon to be occupied by the advancing Allied forces.

    Throughout the Ypres offensive, mustard gas continued to be used in vast quantities. It proved particularly effective against artillery positions. On the 18 Aug, during the Battle of Langemarck, batteries of the 1st Canadian Division were subjected to a concentrated bombardment of mustard gas which resulted in four officers and 179 men becoming casualties and the guns of three batteries being put out of action.

    David Lambert was served as a signaller with A Battery, 150th Brigade Royal Field Artillery remembered that after being gassed, he had to write down what the troops relieving him needed to know as being exposed to gas had left him unable to speak.

    Image: © IWM (Q 3006)

  • 'What happened to me then I’ve no idea'

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    Private Donald Price  suffered a sharpnel wound when a shell containing mustard gas burst near his trench and he was put on a train to Boulogne to recover from both the wound and the effect of the gas. 

    Between mid-October and November, during the first and second battles of Passchendaele that brought the offensive to a close, the Steenbeek valley was continuously saturated with a combination of blue cross (diphenyl chlorasine) gas and mustard gas. The blue cross provoked violent sneezing that forced soldiers to remove their gas masks, exposing them to the more serious effects of the mustard gas.

    Image: © IWM (Q 349)

  • 'It stopped us'

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    Although deaths were relatively few, mustard gas once again proved to be a devastatingly efficient  way of removing thousands of troops from the battlefield, delaying advances and rendering large areas of ground, weapons and equipment unusable.    

    Leonard Ounsworth, who was with the 144th Heavy Battery Royal Garrison Artillery, remembered that gas attacked "stopped" his battery because the  men just couldn't carry on.

    From the Third Battle of Ypres until the end of the war, mustard gas accounted for 90% of all gas cases, and in 1917 alone was responsible for more casualties and deaths than all other types of gas throughout the whole of 1916.

    But despite being by far the most successful chemical weapon used by the Germans, mustard gas ultimately proved not to be a war winning weapon, and during the final year of the war its effectiveness steadily diminished due to a combination of dwindling stocks and the increasing deployment of it by the Allies themselves. 

    Image: © IWM (E(AUS) 825)