 By the time he was 25, he was editor of the "Vancouver World".With the outbreak of World War I in 1914, Odlum received a commission as major of the 7th Battalion of the First Canadian Division of the Canadian Expeditionary Force, second-in-command under Lieutenant-Colonel William Hart-McHarg.Odlum's battalion moved into the front lines in April 1915, and only days later was subjected to the first gas attacks on the Western Front that heralded the Second Battle of Ypres.