Massie, who enlisted in the Australian Imperial Force on 17 August 1914, was commissioned as a second lieutenant in the 4th Battalion on 14 September, served with distinction during the war. His battalion embarked for Egypt in October, and he was promoted lieutenant on 1 February 1915. He took part in Australia's campaign at Gallipoli and in just his second day in the conflict was fortunate to survive a suicidal advance towards the Turkish lines, resulting from orders that were misunderstood by his battalion, when his commanding officer was killed, Massie tried to recover his body. While fighting at Gallipoli he wore a scarlet rag on his right arm so that if he was shot by the Turkish marksmen it would likely be to the arm that stood out and not his left arm which he used for bowling.