 The First World War brought an end to Hornung 's fictional output . His son , Oscar , was killed at the Second Battle of Ypres in July 1915 . Hornung joined the YMCA , initially in England , then in France , where he helped run a canteen and library . He published two collections of poetry during the war , and then , afterwards , one further volume of verse and an account of his time spent in France , Notes of a Camp @-@ <unk> on the Western Front . Hornung 's fragile constitution was further weakened by the stress of his war work . To aid his <unk> , he and his wife visited the south of France in 1921 . He fell ill from influenza on the journey , and died on 22 March 1921 , aged 54 . 
