You may not know, but chemical and biological warfare has been used long before World War One. In the 5th century BC, Spartans used bombs made of sulphur and pitch to overcome the enemy. During ancient times, soldiers sometimes threw bodies of plague victims over the walls of besieged cities, or into water wells. The first deadly gas attack came in April 1915 when the German Army dropped chlorine gas over the Allied trenches in Belgium, Within weeks the British retaliated with a chlorine attack. The deadly rally of chemical warfare was on. In 1918 both sides used mustard gas, which seeped through masks, burning skin and searing lungs. The first international accord on the banning of chemical warfare was agreed upon in Geneva in 1925. Despite the Geneval Protocol the Japanese used chemical warfare against China in 1930. Chemicals were also used during the Iran-Iraq conflict (1980 – 1988), a war that claimed a million victims. Iraq continued to use chemical weapons against the Kurdish minorities in the country. In 1993 another global convention banning the production and stockpiling of chemical warfare agents was signed by more than 100 countries.