Glenbrook Tunnel War One. The first was Chlorine gas which was introduced by the Germans at the Second battle of Ypres in April 1915. This was followed by the use of Phosphene Gas, also introduced by the Germans. These attacked victims' respiratory organs causing coughing and choking. The Germans used Mustard Gas, a more advanced gas, for the first time at Riga (or Yperite) in September 1917. It caused both internal and external blistering in its victims. The blistering was often delayed and remained in the ground for weeks afterwards making capture of infected trenches dangerous. Protection against mustard gas was far
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