<P> Although all major combatants stockpiled chemical weapons during the Second World War, the only reports of its use in the conflict were the Japanese use of relatively small amounts of mustard gas and lewisite in China, and very rare occurrences in Europe (for example some sulfur mustard bombs were dropped on Warsaw on 3 September 1939, which Germany acknowledged in 1942 but indicated had been accidental). Mustard gas was the agent of choice, with the British stockpiling 40,719 tons, the Soviets 77,400 tons, the Americans over 87,000 tons and the Germans 27,597 tons . The destruction of an American cargo ship containing mustard gas led to many casualties in Bari, Italy, in December 1943 . </P> <P> In both Axis and Allied nations, children in school were taught to wear gas masks in case of gas attack . Germany developed the poison gases tabun, sarin, and soman during the war, and used Zyklon B in their 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 . Poison gas played an important role in the Holocaust . </P> <P> Britain made plans to use mustard gas on the landing beaches in the event of an invasion of the United Kingdom in 1940 . The United States considered using gas to support their planned invasion of Japan . </P> <P> The contribution of gas weapons to the total casualty figures was relatively minor . British figures, which were accurately maintained from 1916, recorded that only 3% of gas casualties were fatal, 2% were permanently invalid and 70% were fit for duty again within six weeks . </P>

When was the first time gas was used in ww1