Source: April 1917 war diary.
Find-A-Grave
“Harold Edmund Flower Ralph was born in Essex on 19 August 1887, and having emigrated to Canada attested for the Canadian Overseas Expeditionary Force at Toronto on 12 April 1915. Commissioned Second Lieutenant on 20 January 1917, he served during the Great War with the 18th Battalion on the Western Front from 30 April 1917, and was admitted to the 20th General Hospital suffering from the effects of Gas on 18 August 1917. Repatriated to the U.K., he was discharged on medical grounds on 30 November 1918, and died in Toronto on 13 October 1963.”
History of the 18th Battalion CEF, "The Fighting Eighteenth" 