Inscribed by the artist, as title. While there is nothing to indicate where or when this First World War event took place (and it may just be an impression rather than specific), it is most likely to be on the Western Front in France or Belgium. It may have been done as the basis of a published magazine illustration. Chlorine gas was first used in April 1915, phosgene gas in December 1915 and mustard gas in July 1917.