Poison Gas
Poison Gas, made of chlorine was first successfully used on 22 April 1915, at the start of the Second Battle of Ypres by the Germans. This was not truly the first time it was used though. The French used tear gas grenades against the Germans in the beginning weeks of the war. The reason this was instituted was a means of ending the trench stalemate. The effects of chlorine gas were severe. Within seconds of inhaling its vapor it destroyed the victim's respiratory organs, bringing on choking attacks.