[1] The son of a light horseman who served in the Gallipoli and Palestine campaigns during the First World War, Hughes joined the Australian Army in 1937 and graduated from the Royal Military College, Duntroon as a lieutenant in the infantry in 1939.

[1][4] In 1943 Hughes was posted to Headquarters 1st Australian Corps and was involved in the amphibious landing at Nassau Bay, as a liaison officer with the American forces during the New Guinea campaign.

[6] His younger brother, Jim, had previously served in the battalion as a platoon commander, and had been awarded the Military Cross for his actions during the Battle of Maryang San.

[1][7] Commanding 3 RAR during the static phase of the war he believed in active patrolling, but was doubtful of the value of operations to capture Chinese prisoners and the casualties that were incurred during these missions.

[3] During 1967–68 Hughes commanded the 1st Australian Task Force (1 ATF) based in Phuoc Tuy Province, South Vietnam, which was involved in counter-insurgency operations against the Viet Cong.

[9] Meanwhile, 1 ATF was reinforced, with 3 RAR arriving in December 1967 to bring the task force up to full strength with three infantry battalions supported by armour, artillery, aviation and engineers.

[11] Hughes' period in command witnessed heavy fighting during Operation Coburg (24 January − 1 March 1968), which was mounted in response to the communist Tet Offensive, and the Battle of Coral–Balmoral (12 May – 6 June 1968).