[3] Hardman began his military career in 1916 as a seventeen-year-old private in the Artists Rifles—part of the London Regiment—and joined the Royal Flying Corps (RFC) early the following year.

98 Squadron to Mons; in a dogfight that resulted in the loss of ten British aircraft, Hardman sent two German Fokker D.VIIs down in flames.

[5] His "cool judgment and skill in leading" during this action earned him the Distinguished Flying Cross; the award was promulgated on 11 February 1919.

[2][5] The life expectancy of even an experienced RFC pilot on the Western Front was as little as three weeks;[10][11] years later, Hardman admitted that he was still surprised he had survived.

[1][12] On 18 October 1921, he joined the Royal Air Force (RAF) with a short-service commission as a flying officer, and was posted to India's North-West Frontier in 1922.

[22][23] On 8 July 1930, Hardman married Dorothy Ursula Ashcroft Thompson at St George's, Hanover Square, in London; the couple had two sons and a daughter.

[14][24] Tasked with bombing and transport duties, the squadron operated Vickers Victorias and pioneered the air route from Lagos to Khartoum in 1934.

[30][31] On first meeting the then Air Commodore in his headquarters in Comilla one was immediately aware of an exceptionally dignified bearing, a considerable presence, great humour; there was much leg-pulling and light-hearted banter, the whole atmosphere was very much at ease.

[1][33] He was appointed an Officer of the Order of the British Empire on 11 July 1940 for "distinguished services rendered in recent operations",[34] and mentioned in despatches on 1 January 1941.

[38] He was assigned to Air Command South East Asia (ACSEA) as the deputy commander—and RAF component commander—of the Combat Cargo Task Force (CCTF).

[50] The decision by Australia's Prime Minister, Robert Menzies, to appoint an RAF officer caused resentment in the RAAF.

This was compounded when Menzies stated his reason as being that there was "no RAAF officer of sufficient age, or operational experience, to take the post of Chief of the Air Staff", which appeared to ignore the wartime records of such figures as John McCauley and Frederick Scherger.

Britain's CAS, Marshal of the Royal Air Force Sir John Slessor, was, somewhat reluctantly, responsible for fulfilling the Australian Government's request for a suitable officer.

In putting forward Hardman as the "outstanding candidate" for the Australian post, Slessor tried to avoid what he called "the follies of some years ago", referring to Air Chief Marshal Sir Charles Burnett's controversial tenure as CAS on secondment from the RAF early in World War II.

[52] While doing away with the area command structure that had been favoured by Jones, Hardman carried on his predecessor's support for the local aircraft industry.

[55] He also formed a policy agreement with the Chief of the Naval Staff, Vice Admiral Sir John Collins, covering joint responsibility and cooperation for maritime warfare.

[57] He was appointed a Knight Commander of the Order of the Bath in the Queen's Birthday Honours promulgated on 5 June 1952,[58] and raised to substantive air marshal on 1 July.

He maintained that the only way to attain "true and enduring air superiority" was by attacking the enemy's vital centres, which included its means of producing fighters.

[1][61] Towards the end of his tenure as CAS, Hardman gave an interview in which he criticised Army and Navy operations against a backdrop of continuing interservice rivalry for the defence budget.

"[63] In contrast to the initial disquiet at his appointment, upon his departure from Australia Hardman was described by The Age as "the outstanding CAS in the RAAF's history", a "brilliant organiser", and a "master of the theory of air power".

[68] That October, he presided over the inquiry into the fatal crash of Vulcan XA897 at Heathrow Airport after its maiden round-the-world flight, the only survivors of the six crew members being the pilot and Air Marshal Sir Harry Broadhurst.

[72] In February 1963, he succeeded Air Chief Marshal Sir Douglas Evill as the RAF Benevolent Fund's honorary county representative for Hampshire.