British war crimes September 1915 and continued their usage for the remainder of the war. This was done in retaliation for the use of chlorine by Imperial German Army the preceding April. Following the Imperial German Army's use of poison gas at Ypres, the commander of II Corps, Lieutenant General Sir Charles Ferguson, had said of poison gas: Mustard gas was first used effectively in World War I by the German army against British and Canadian soldiers near Ypres, Belgium, in 1917 and later also against the French Second Army. The name "Yperite" comes from its usage by the German army near the
Action of 25 September 1917 increase the accuracy of German artillery-fire as the British attacked. On 23 September, Crown Prince Rupprecht wrote in his diary that the higher ground at Zonnebeke and Gheluvelt was vulnerable to another British attack and that it was vital that the German counter-attack tactic did not fail again. Next day, Rupprecht wrote that he hoped that another British attack would be delayed, as the 4th Army had insufficient reserves for the whole of the active front east of Ypres. Rupprecht ordered a (methodical counter-attack) against the British flank between the Menin Road and Polygon Wood, which was longer after the