Sulfur mustard later also against the French Second Army. The name Yperite comes from its usage by the German army near the town of Ypres. The Allies did not use mustard agent until November 1917 at Cambrai, France, after the armies had captured a stockpile of German mustard shells. It took the British more than a year to develop their own mustard agent weapon, with production of the chemicals centred on Avonmouth Docks. (The only option available to the British was the Despretz–Niemann–Guthrie process). This was used first in September 1918 during the breaking of the Hindenburg Line. Mustard agent was dispersed
Action of 22 October 1917 Action of 22 October 1917 The Action of 22 October 1917 was an attack during the Third Battle of Ypres in the First World War by the British Fifth Army and the French First Army against the German 4th Army. British attacks had been repulsed at Passchendaele by the 4th Army at the Battle of Poelcappelle (9 October) and the First Battle of Passchendaele (12 October). While the British waited for another dry spell and the completion of plank roads up to the new front line, the Canadian Corps and fresh British divisions were transferred to Flanders by the British