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 September, German troops were to conduct a on the Fifth Army front opposite the 20th (Light) Division in XIV Corps and a bigger attack against the X Corps front, in the centre of the Second Army, south of the I Anzac Corps in Polygon Wood. The 50th Reserve Division had been the "Eingreif" division for from and was moved south to the Menin area as a reserve. The division relieved the Bavarian "Ersatz" Division on 21 September, Reserve Infantry Regiment 231 (RIR 231) south of the Menin road, RIR 230 north of the road to the Reutelbeek and RIR 229