Askin enlisted as a Private in the Second Australian Imperial Force on 30 March 1942. An instructor with the 14th Infantry Training Battalion at Dubbo, he was appointed Acting Corporal, then reverted to Private. In November 1942 he joined the 2/31st Infantry Battalion in New Guinea, where he served for two months. He was in New Guinea for another six months from July 1943. Landing at Balikpapan, Borneo, in July 1945, Askin was promoted to Sergeant under Lieutenant Colonel Murray Robson. When hostilities ceased, he unsuccessfully attempted to set up an import business in Bandjermasin. Returning to Australia in February 1946, he was demobilised on 22 March.