Service was 41 when World War I broke out; he attempted to enlist, but was turned down "due to varicose veins." He briefly covered the war for the Toronto Star (from December 11, 1915, through January 29, 1916), but "was arrested and nearly executed in an outbreak of spy hysteria in Dunkirk." He then "worked as a stretcher bearer and ambulance driver with the Ambulance Corps of the American Red Cross, until his health broke." Convalescing in Paris, he wrote a new book of mainly war poetry, Rhymes of a Red Cross Man, in 1916. The book was dedicated to the memory of Service's "brother, Lieutenant Albert Service, Canadian Infantry, Killed in Action, France, August 1916." Robert Service received three medals for his war service: 1914–15 Star, British War Medal and the Victory Medal.