First World War
Chemical weapons were deployed for the first time in warfare. Chlorine and phosgene gases were released from canisters and dispersed by the wind. It is estimated that 90,000 died as a result. In 1916 the British government established the Porton Down facility in Wiltshire to research and develop chemical weapons.
Britain's invasion of Soviet Russia
In 1919 Winston Churchill authorised the use of chemical weapons in northern Russia as part of the attempt to overthrow the new Soviet regime.