He volunteered for overseas service soon after the war began in September 1939, and served in the Middle East and the Battle of Greece with the 2/2nd Battalion.

After the war, Green briefly returned to civilian life and part-time military service as commanding officer of the 41st Battalion.

After a brief period of training in Japan, where 3 RAR was part of the British Commonwealth Occupation Force, Green led the battalion to Korea in late September.

[1][2] With the outbreak of World War II, Green volunteered for overseas service and on 13 October 1939, he enlisted in the Second Australian Imperial Force (2nd AIF) which was being raised for that purpose.

[1] Green initially served as one of the 2/2nd's platoon commanders,[3] but accidentally injured himself, and missed out on taking part in 6th Division's first combat action, which took place during the North African campaign between December 1940 and January 1941.

They were quickly overwhelmed by the larger German forces,[1][4] the 2/2nd Battalion losing 44 killed or wounded and 55 taken prisoner in desperate fighting.

Disguised as "English civil engineers" they caught a train to Alexandretta (modern İskenderun), from where they boarded a Norwegian ship to Port Said, Egypt.

According to Margaret Barter, the author of his entry in the Australian Dictionary of Biography, he contributed a "sensitive account" of the campaign to a battalion history, Nulli Secundus Log, which was published in 1946.

[4] On the way home, the 16th Brigade was diverted to defend Ceylon (modern Sri Lanka), where the 2/2nd Battalion was part of the garrison between 27 March and 13 July.

On 30 December, having been substantively promoted to major in September, he was posted as an instructor to the First Australian Army's Junior Tactical School in Southport, Queensland.

He married Edna Olwyn Warner at St Paul's Anglican Church, Ulmarra, New South Wales, on 30 January 1943; his best man was his former commanding officer, Colonel Frederick Chilton.

[8] On 30 December 1944, Green arrived in the town of Aitape, on the north coast of New Guinea,[2] where the 6th Division was taking over responsibility for the area from US forces.

[15] As part of this offensive, the 2/11th and the 2/7th Commando Squadron were sent on a wide sweeping movement inland to cut off the Japanese, who were abandoning Wewak in the face of pressure from the 2/4th Battalion and withdrawing their main force into the Prince Alexander Mountains.

77 Squadron RAAF and infantry from the 3rd Battalion, Royal Australian Regiment (3 RAR), both of which were stationed in Japan as part of the British Commonwealth Occupation Force (BCOF).

[28] When the Australian government committed 3 RAR, Army Headquarters determined that it would be led by an officer who had served in World War II and had a distinguished record.

[31] Green's battalion joined Brigadier Basil Coad's 27th British Commonwealth Brigade, part of the force under the Commander-in-Chief United Nations Command, General of the Army Douglas MacArthur.

In one incident, Green's second-in-command, Major Ian Bruce Ferguson, captured 1,600 North Koreans with just an interpreter, a loudspeaker and a tank.

To cut off KPA units retreating towards the Yalu River, the US 187th Airborne Regimental Combat Team was parachuted around Yongju north of Pyongyang.

[32] The battle began as 3 RAR led the brigade north of Yongju when C Company and Green's battalion tactical headquarters following it were attacked from front and rear by a KPA force of around 1,000 soldiers.

C Company aggressively counter-attacked, and while the KPA troops fought "with desperate bravery" and regrouped in an apple orchard to the east of the road, the Australians, supported by US tanks, quickly prevailed.

[39] Green has been credited with the excellent performance of the battalion in its first major action, Coad observing that he was "a fine fighting soldier, so quiet in his manner ... he inspired confidence, both with his superiors and subordinates".

[39] When the lead elements of 3 RAR reached the Taeryong River near Kujin it found KPA engineers had destroyed the centre span of the bridge.

[40][41] When aerial reconnaissance identified KPA forces on the high ground,[42] Green ordered the patrol to withdraw to the near side of the river, which they did, bringing ten prisoners with them.

[32] Airstrikes and the battalion mortars were called in onto the KPA positions across the river,[43][44] and Green ordered D Company to clear nearby Pakchon.

Aerial reconnaissance indicated that a KPA force of around 500–600, supported by tanks and self-propelled guns (SPGs), had established well-constructed and camouflaged defensive positions on a thickly wooded ridgeline south of the town.

[60][61] Although the North Koreans managed to overrun parts of the company position, counter-attacks restored the situation after two hours of fierce fighting.

[52] The battalion moved forward to a reserve position on the Talchon River on 30 October,[62] while other brigade elements cleared Chongju itself, securing it by 17:00.

Five of the shells landed on the forward slope, while the sixth cleared the crest and detonated to the rear of the C Company position after hitting a tree.

[66] A popular and respected commanding officer, Green's loss was keenly felt by the Australians,[66] and according to Barter, "cast a pall of gloom over his battalion".

[1][73] According to Barter, Green's career as a battalion commander in New Guinea and Korea had been "exemplary",[1] and serving Australian soldiers were still inspired by it at the time she wrote his entry in 1996.