Mervyn enlisted on 29 Apr 1941 with prior service in the Citizens Military Force (Reserves) 16th Battalion. He was promoted Acting Corporal on 12 May 1941 and was an original member of the unit, embarking aboard “S.S. ZEALANDIA” on 8 Dec 1941 for Timor as a Corporal in No 1 Sect, “A” Platoon. He was promoted to Sergeant on 16 Nov 1942 and embarked with the unit, for Australia aboard the Royal Dutch destroyer “Tjerk Hiddes” on 16 Dec 1942.
After leave and reorganization he embarked with the unit for New Guinea as the Troop Sergeant in the Headquarters Sect, “A” Troop, aboard S.S. “DUNTROON” on 17 Jun 1943. He left the unit on 4 Mar 1944 and returned to Australia aboard "ORMISTON" on 30 Mar 1944. He transferred to 1st Australian Commando Training Squadron on 22 Jun 1944 as an instructor and then to Western Command Rehab Unit on 11 Sept 1945.
He was discharged on 26 Feb 1946.
He was entitled to the 1939-45 Star, Pacific Star, War Medal and Australian Service Medal 1939-45, pictured below.