Although he was aged almost 40 when World War I began, Lee enlisted in the 4th Battalion of the Black Watch, which was the territorial battalion for Dundee, in 1914 and eventually rose to the rank of Sergeant. He and eight other Dundee journalists who joined the battalion were dubbed 'Fighter-Writers'. Lee's enlistment was despite his age, health problems (he was suffering from asthma) and the fact many of his associates in the labour movement in Dundee strongly opposed the war. Caroline Brown, Matthew Jarron and Kenneth Baxter, have noted that it is possible Lee was inspired by the fact his grandfather had fought at Waterloo (Lee wrote a poem about this in 1915), or was swept up in a wave of patriotism which swept Dundee at this time. However, as they note, whatever his reasons were, it is unlikely he realised his involvement in the War would prove to be the key point of his literary career.