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 defeat German counter-attacks, by advancing no more than and then consolidating their positions, preferably on reverse-slopes. When the Germans counter-attacked, they would encounter a British defence-in-depth protected by artillery and suffer many casualties to little effect, rather than the small and disorganised groups of infantry that the Germans had driven back on 31 July, After the big defeat at the Battle of the Menin Road Ridge on 20 September, the 4th Army changed the organisation of regiments and battalions in their defensive positions. During August, each German front-line division had kept two regiments in the front position, with all six