Chlorine Chlorine was the first chemical to be specifically and effectively used as a lethal agent in World War I, although "non-lethal" chemical harassing agents had been used from early on in the war. K-Stoff K-Stoff was introduced by the Germans in June 1915 as a more lethal replacement for chlorine. A low-boiling liquid (boiling point 1 degree of Celcius), it was loaded into

read more: Lethal Agents Used for Weapons in the World War I