The Australian Air Force was formed on 31 March 1921. King George V approved the prefix "Royal" in June 1921 and it became effective on 31 August 1921. The RAAF then became the second Royal air arm to be formed in the British Commonwealth, following the British Royal Air Force (formed on 1^st April 1918).

The service rapidly expanded during World War II and at its height, was the fourth largest air force in the world, consisting of 53 squadrons based in the Pacific and 17 squadrons in Europe.

Shortly after the declaration of war in Europe, although Australia's air force was small – consisting of just 246 aircraft – the Australian government offered to send six squadrons to Britain to fight, in addition to the 450 Australians who were already serving in the ranks of the Royal Air Force at the time. The RAAF already had one squadron in the United Kingdom, No. 10 Squadron RAAF, which had been dispatched earlier in the year to take ownership of nine Short Sunderland flying boats and return them to Australia. They subsequently took place in their first operational mission on 10 October 1939, when they carried out a sortie to Tunisia. 

To rapidly expand, Australia joined the Empire Air Training Scheme, under which flight crews received basic training in Australia before travelling to Canada or Rhodesia for advanced training. These crews were then posted to operational units. A total of 17 RAAF bomber, fighter, reconnaissance and other squadrons served initially in Britain, and/or with the Desert Air Force, in North Africa and the Mediterranean.^]

An Australian Hampden from No. 455 Squadron RAAF at RAF Leuchars in May 1942.

With British manufacturing targeted by the Luftwaffe, the Australian government created the Department of Aircraft Production (DAP), which was later known as the Government Aircraft Factories, to supply Commonwealth air forces, and the RAAF was eventually provided with large numbers of locally-built versions of British designs like the Beaufort torpedo bomber.^[

In the European Theatre of World War II, RAAF personnel were especially notable in RAF Bomber Command: although they represented only two percent of all RAAF personnel during the war, they accounted for 23% of the total number killed in action. This statistic is further illustrated by the fact that No. 460 Squadron RAAF, mostly flying Avro Lancasters, had an official establishment of about 200 aircrew and yet had 1,018 combat deaths. The squadron was therefore effectively wiped out five times over. 

An Australian Beaufighter flying over the Owen Stanley Range in New Guinea in 1942

The beginning of the Pacific War—and the rapid advance of Japanese forces—threatened the Australian mainland for the first time. The RAAF was unprepared for the emergency, and had negligible forces available for service in the Pacific. Its four squadrons based in Malaya – Nos. 1, 8, 21 and 453 – equipped with a mixture of Hudsons, Wirraways and Buffalos, were the first to go into combat, but they suffered heavily against Japanese during the Malayan Campaign and the subsequent fighting on Singapore, highlighting the fact that the Japanese held the upper hand in the air. 

In response, some RAAF squadrons –  such as No. 452 Squadron  – were transferred from the northern hemisphere—although 15 remained there until the end of the war. Shortages of fighter and ground attack planes led to the acquisition of US-built P-40 Kittyhawks, and the rapid design and manufacture of the first Australian fighter, the CAC Boomerang. RAAF Kittyhawks, such as those operated by Nos. 75, 76 and 77 Squadrons, came to play a crucial role in the New Guinea and Solomon Islands campaigns, especially in the Battle of Milne Bay and in the Kokoda Track campaign. 

By late 1945, the RAAF had received or ordered about 500 P-51 Mustangs, for fighter/ground attack purposes. The Commonwealth Aircraft Corporation initially assembled US-made Mustangs, but later manufactured most of those used. The RAAF's main operational formation, the First Tactical Air Force, comprised more than 18,000 personnel and 20 squadrons; it had taken part in the Philippines and Borneo campaigns and was scheduled to participate in the invasion of the Japanese mainland, Operation Downfall. So too were the RAAF bomber squadrons in Europe, as part of the proposed Tiger Force. However, the war was brought to a sudden end by the US nuclear attacks on Japan. 

As a result of the Empire Air Training Scheme, about 20,000 Australian personnel had served with other Commonwealth air forces in Europe during World War II. A total of 216,900 men and women served in the RAAF, of whom 9,780 lost their lives. At war's end, a total of 53 RAAF squadrons were serving in the Pacific and a further 17 in Europe. With over 152,000 personnel operating nearly 6,000 aircraft it was the world's fourth largest air force, after those of the USA, the USSR and the UK.

In the Korean War, Mustangs from No. 77 Squadron, stationed in Japan with the British Commonwealth Occupation Force, were among the first United Nations aircraft to be deployed in ground support, combat air patrol, and escort missions. 

During the Vietnam War, from 1966–1972, the RAAF contributed squadrons of Caribou Short Take Off and Landing (STOL) transport aircraft (No. 35 Squadron), UH-1 Iroquois helicopters (No. 9 Squadron) and English Electric Canberra bombers (No. 2 Squadron).

The Canberras flew a large number of bombing sorties, two were lost (in 1970 and 1971). Two crew members were killed, two squadron members died of disease, and three from accidents during the war. One of the Canberras lost (A84-228) was brought down by a surface-to-air missile from which the crew safely ejected and were rescued by helicopter. The other (A84-231) was lost near Da Nang, during a bombing run. Its exact location and fate of its crew were unknown for 28 years, when it was located and their remains were returned to Australia.

RAAF transport aircraft also supported anti-communist ground forces. The UH-1 helicopters were used in many roles including Dustoff (medical evacuation) and Bushranger Gunships for armed support. 

Military airlifts were conducted for a number of purposes in the intervening decades, such as the peacekeeping operations in East Timor from 1999. Australia's combat aircraft were not used again in anger until the Iraq War in 2003, when F/A-18s from No. 75 Squadron operated in the escort and ground attack roles. 

Three F/A-18 Hornets in 2012

On 31^st March 2021, the R.A.A.F. celebrates its 100 the anniversary.

F-35 – Latest addition to the RAAF

Compiled by Bob Greeney
With acknowledgement to Wikipedia