Thomas was an original member of the unit, embarking aboard “S.S. ZEALANDIA” on 8 Dec 1941 for Timor as a Private in No 1 sect, “A” Platoon. After the campaign on Timor, he embarked with the unit, for Australia aboard the Royal Dutch destroyer “Tjerk Hiddes” on either 11 Dec 1942 or 16 Dec 1942, as the embarkation rolls do not differentiate.
After leave and reorganization he embarked with the unit as a Corporal in No 3 sect, “A” Troop for New Guinea aboard S.S. “DUNTROON” on 17 Jun 1943 and returned to Australia with them aboard “TAROONA” on 3 Sept 1944.
Thomas was Mentioned in Despatches, London Gazette, 8 Mar 1945 and in the Commonwealth of Australia Gazette, No 54-15 Mar 1945.
After further leave and reorganization, he embarked for New Britain aboard “TAROONA” on 9 Apr 1945 with the unit as a Lance Sergeant.
He was commissioned and as a Lieutenant, he transferred to Headquarters, South Australia, 9 Oct 1945 and then to Australia Staging Camp, 7 Jan 1946.
He was discharged on 19 Jul 1946.