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
CR gas insurgent group in Sri Lanka used CR gas against government forces that were on an offensive to flush and defeat these insurgents during September 2008. Its use hindered the army's progress but ultimately proved ineffective in preventing the army from overrunning LTTE positions. This is one of the first few cases of insurgents using CR gas as an insurgent weapon. In the June 2013 protest against the Turkish government, Turkish police allegedly used CR gas on protesters in Istanbul. Doctors in a makeshift first aid post in a Mosque judged it as such. In Ukraine, CR gas is commonly used