 During the First World War, he reached the rank of major in the Canadian Expeditionary Force (1915 – 1918), serving overseas, and involved in the Khaki College as the commanding officer.He retired at seventy years of age and from 1954 was the proprietor of the well-known Dora Hood's Book Room booksellers.Wallace died on Wednesday, 11 March 1970 in Toronto and was buried at the Mount Pleasant Cemetery, Toronto, survived by his wife and children.