Analysis of archival correspondence, the daily logs of troopships transporting soldiers to Europe and the Commonwealth War Graves Commission database for soldier deaths from pneumonia and influenza across Canada indicate that influenza was more common during the summer of 1918 than previously thought. Evidence of pandemic influenza so close to the outbreak of the fall wave calls into question the storyline of a mutated virus causing the emergence of the fall wave of the 1918 influenza pandemic. This highlights the significance of other host, social and environmental circumstances, many related to the First world war, that may have contributed to the severity and timing of pandemic waves in Canada.