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
Opposing forces in the Polish September Campaign Poland successfully used 10 regular armoured trains against German forces, which were unprepared to face this kind of combat vehicle considered in 1939 so obsolete by German planners to be given any serious consideration. Although the trains proved indeed vulnerable to air attack, losses incurred against Polish trains ("Śmiały" Armored Train destroyed nearly 100 German tanks during the battles around Mokra village) convinced the Germans to reintroduce this type of vehicle into their own army after the September Campaign. Experience in the Polish-Soviet War (1919–1921), the only recent, major conflict the independent Second Polish Republic took part in, shaped Polish