Lieutenant Donald R Grantham MC RE, holding M Generators adapted as aircraft bombs, Lake Onega seaplane base, 1919. (RE Museum)
The first time chemical weapons were used from aircraft was during British operations against Bolshevik forces around Archangel and Murmansk in 1919. Below is my article on the episode which was published in the Imperial War Museum Review (No. 12, 1999). (Click each page to enlarge). Scroll to the bottom for more articles.
Article: understanding Chemical Warfare in the First World War
Understanding Chemical Warfare in the First World War
Yellow Cross: The advent of Mustard Gas in 1917
Myths of Messines: the ‘Lost Mines’