Zyklon B
Hydrogen cyanide had been discovered in the late 18th century and was usually used in California for the fumigation of citrus trees. In 1919, the Deutsche Gesellschaft für Schädlingsbekämpfung mbH (Degesch) was founded in Germany. This was a state-controlled group to investigate military uses of the chemical. The new product was marketed as a pesticide, Zyklon, but was soon banned as being similar to a mixture used in World War I as a weapon.