 Curlewis had wanted to enlist in World War I but his parents would not permit this until he was 18 years old, by which time to armistice was signed.He became an officer in cadet corp at school in 1920 and at university joined the University Regiment as an orderly room corporal becoming an officer after a year before the militia was disbanded.He was commissioned in the Militia on 6 June 1939 one week before the start of the war and transferred to the AIF, in September 1940, in February 1941 he was a Captain, General Staff Officer, in Headquarters 8th Division AIF, in Malaya and Singapore, he was taken prisoner by the Japanese with the surrender of Singapore on 15 February 1942.