[2] Sweeting joined the Second Australian Imperial Force (2nd AIF) on 23 July 1940 and was posted to the 2/4th Field Ambulance.
[2] After leaving the army, Sweeting continued to work for Long as a research assistant on the official history series Australia in the War of 1939–1945.
He also authored three chapters in one of the volumes, covering the experiences of Australian prisoners of war held by Japan.
[3][5] After Long retired in 1963, Sweeting became the acting editor of the official history series, and remained in this role until 1970 when the last volume was published.
[8] Sweeting retired from the AWM in March 1979; his final position there was Assistant Director, History and Publications.