Ypres east of the town. The first gas attack occurred against Canadian, British, and French soldiers, including both metropolitan French soldiers as well as Senegalese and Algerian tirailleurs (light infantry) from French Africa. The gas used was chlorine. Mustard gas, also called Yperite from the name of this town, was also used for the first time near Ypres, in the autumn of 1917. Of the battles, the largest, best-known, and most costly in human suffering was the Third Battle of Ypres (31 July to 6 November 1917, also known as the Battle of Passchendaele), in which the British, Canadian, ANZAC, and
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