<Dd> Case four . Aged 39 years . Gassed 29 July 1917 . Admitted to casualty clearing station the same day . Died about ten days later . Brownish pigmentation present over large surfaces of the body . A white ring of skin where the wrist watch was . Marked superficial burning of the face and scrotum . The larynx much congested . The whole of the trachea was covered by a yellow membrane . The bronchi contained abundant gas . The lungs fairly voluminous . The right lung showing extensive collapse at the base . Liver congested and fatty . Stomach showed numerous submucous haemorrhages . The brain substance was unduly wet and very congested . </Dd> <P> The distribution of gas cloud casualties was not only limited to the front . Nearby towns were at risk from winds blowing the poison gases through . Civilians rarely had a warning system put into place to alert their neighbours of the danger . In addition to poor warning systems, civilians often did not have access to effective gas masks . Also, when the gas came to the towns over the wind, it could easily get into houses through open windows and doors . An estimated 100,000 - 260,000 civilian casualties were caused by chemical weapons during the conflict and tens of thousands (along with military personnel) died from scarring of the lungs, skin damage, and cerebral damage in the years after the conflict ended . Many commanders on both sides knew that such weapon would cause major harm to civilians as wind would blow poison gases into nearby civilian towns but nonetheless continued to use them throughout the war . British Field Marshal Sir Douglas Haig wrote in his diary: "My officers and I were aware that such weapon would cause harm to women and children living in nearby towns, as strong winds were common on the battlefront . However, because the weapon was to be directed against the enemy, none of us were overly concerned at all ." </P> <P> None of the First World War's combatants were prepared for the introduction of poison gas as a weapon . Once gas was introduced, development of gas protection began and the process continued for much of the war producing a series of increasingly effective gas masks . </P> <P> Even at Second Ypres, Germany, still unsure of the weapon's effectiveness, only issued breathing masks to the engineers handling the gas . At Ypres a Canadian medical officer, who was also a chemist, quickly identified the gas as chlorine and recommended that the troops urinate on a cloth and hold it over their mouth and nose . The first official equipment issued was similarly crude; a pad of material, usually impregnated with a chemical, tied over the lower face . To protect the eyes from tear gas, soldiers were issued with gas goggles . </P>

When was mustard gas used in world war 1