Born into a Roman Catholic family in 1915, Serong's opposition to communism led him to join the army, graduating from the Royal Military College, Duntroon, in 1937.

Leaving the army in 1968, he remained in Vietnam as a security and intelligence adviser to the South Vietnamese government, as well as working for the Rand organisation, Hudson Institute and other corporations, and consulting to the Pentagon and several US presidents.

In later life he maintained an interest in Australian defence issues and was at times a controversial figure due to his support for several citizens' militia groups, conspiracy theories and right-wing political causes.

After winning a scholarship he attended St Kevin's College in 1931, where he was later influenced by its culture of Irish Roman Catholicism, notions of Australian—as opposed to British—patriotism, and a belief in the constant struggle between "the forces of freedom and atheistic communism".

Subsequent postings included Fort Largs near Adelaide to help raise and train Militia and develop the artillery installation there, before returning to Queenscliff as an instructor in 1940.

[11][13] Serong deployed to New Guinea in November 1942 as a major, posted to the operations staff of the 6th Division in Port Moresby, just as the Australians halted the advance of the Japanese at the height of the Kokoda Track campaign.

[11] In 1943 Serong served as General Staff Officer 2 with the combined 6th and 7th Divisions on the Atherton Tableland in Far North Queensland, where they were resting and retraining prior to conducting further operations.

[15] Although serving more time in training roles than in combat, during the war Serong had made important contacts with whom he would later work in future postings, including Colonel Reg Pollard, who went on to become Chief of the General Staff (CGS), and Colonel Charles Spry, later the Director of Military Intelligence and the Director General of the Australian Security Intelligence Organisation (ASIO).

[22] Under his direction the course at Canungra taught soldiers automatic responses and contact drills to cover the situations they might encounter in jungle warfare, emphasising instinctive shooting and patrolling, as well "battle inoculation" and physical conditioning.

[23] These skills underpinned the Australian Army's methods of dispersed patrolling in small groups moving quietly through the jungle, techniques utilised while fighting the Japanese in New Guinea during the Second World War, and later in Malaya and Vietnam.

[25] Following its independence from Britain in 1948, Burma had been fighting against ethnic unrest and Chinese Nationalist Kuomintang irregulars, and several Burmese Army officers had trained in Australia in the 1950s.

[30] While in Burma Serong's expertise brought him to the attention of the US Central Intelligence Agency (CIA), and as a result he was later invited to supervise counter-insurgency programs in Vietnam.

[20] In February 1962 he wrote to Pollard, by then CGS, to suggest the deployment of a small team of Australian officers under his command to South Vietnam to work with the US advisory group there.

[29] Soon after the Burmese Army staged a coup, seizing control and moving the country towards communist China, after which Serong made arrangements to leave.

[32] The award had been made on Pollard's recommendation on the basis of Serong's work at Canungra and its influence on the training of the post-war Australian Army during "its formative period".

Pollard wrote that "...the position that establishment now occupies in the Australian Army and its reputation overseas is due in great measure to the foresight and determination shown by Colonel Serong."

He believed that the extent of Serong's influence on the Army's training had been because of his "originality of mind" and "strength of character" which had allowed him to enact "ideas and techniques which a less determined person might not have succeeded in doing.

In August 1964, Sir Walter Cawthorn, then head of the Australian Secret Intelligence Service (ASIS), had instructed Serong to "...Get me ten years...", time that had to be bought to strengthen the other nations of the region against insurgency, as well as to destroy the Soviet Union economically.

During the 2+1⁄2 years he led the team he had worked hard to remain in personal contact with its members despite their geographic dispersion, and on occasion while visiting advisors in outstations he had become involved with clashes with the enemy during which his courage and leadership "contributed to the success of operations".

[48][49] Blair later wrote that Serong had accepted the defence of South Vietnam from communism as his "personal mission",[50] and his decision to take an early retirement had been due to his increasing involvement with US organisations, the value they placed on his work and his profile as an international figure, as well as a growing "emotional distance" from the Australian Army and its senior leadership.

He also instructed at the National Defense College of South Vietnam and worked for the Rand organisation, Hudson Institute and other corporations, preparing strategic analyses.

He also supported conspiracy theories about the Port Arthur shooting in 1996 and allegations of government corruption (later found to have been based on a hoax, albeit unbeknown to Serong) as well as speaking on Australian defence issues.