Phil Agnew first served in the militia in 1940. He enlisted in June 1940 and was discharged in August due to the manpower regulations, having attained the rank of corporal while serving with Northern Command Signals.
At that early stage of the war, Phil was working in Brisbane as an apprentice electrician with the City Electric Light Company, which was deemed as a reserve occupation. In May 1942, he gained permission to join the Royal Australian Air Force (RAAF).
Phil trained in Melbourne and was then sent to northern Australia. He was attached to the Mobile Fighter Sector, which supported the Spitfire fighter squadrons based in Darwin. The Mobile Fighter Sector was set up 100 miles (161km) south of Darwin at Coomalie Creek. There, Phil work alongside No 31 (Beaufighter) Squadron, in which his brother was a navigator.
Initially Phil worked as ground maintenance. Later, he applied to join the air crew and was accepted. He trained in many towns and cities including Adelaide, Victor Harbour, Melbourne, Ballarat and Mount Gambier. Phil qualified as a navigator and wireless operator. He was then assigned to Section 22 in General MacArthur's headquarters in Brisbane, where he worked with Field Unit No 6. While working with this unit, he was attached to the 380th American Bomb Group in which he and other Australians flew with the American squadrons. Their main task was to identify Japanese anti-aircraft positions.
Phil flew in Liberator bombers with No 528 Squadron USAAF against targets in Formosa, the South-East Asian mainland, and Legaspi in the Philippines.
He discharged from the RAAF on 3 December 1945 as a Flying Officer.