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 25 September 1917 removing more guns from the Third Army and Fourth Army, which were further south in Artois and Picardy. The increased amount of heavy artillery was to be used to destroy German concrete shelters and machine-gun nests, which were more numerous in the German battle zones, than the outpost zones which had been captured in July and August and to engage in more counter-battery fire. Few German concrete pill-boxes and machine gun nests had been destroyed during earlier preparatory bombardments and attempts at precision bombardment before attacks had also failed. The and guns and howitzers in the Second Army on 31