One of the distinguishing features of the First World War was the widespread use of chemical weapons. Chemical gases of various lethality, including mustard gas, phosgene and tear gas, were used to disable and kill enemy defenders. Although chemical weapons played a major role during the Great War, its usage can be dated to a much earlier period of history.
One of the earliest references to the use of chemical weapons in western literature can be found in the Greek myth of Heracles, in which the hero dips his arrows in the blood of the Hydra to make them toxic. It has also been claimed that poisoned arrows were mentioned by Homer in both his epics, the Iliad and the Odyssey.
