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
German Type U 93 submarine German Type U 93 submarine Type 93 was a class of U-boats built during World War I by the Kaiserliche Marine. Type 93 U-boats carried 16 torpedoes and had various arrangements of deck guns. As with the type 81 and 87, some had only one SK L/30 deck gun while others had a single SK L/45 gun and some were initially equipped with both. In 1917 some of the boats were refitted with a single 10.5 cm gun and 220 rounds. These boats carried a crew of 39 and had excellent seagoing abilities with a cruising range of around .