Formed in late 1917, the squadron operated on the Western Front as part of the Australian Flying Corps until the armistice in November 1918.

It was disbanded in early 1948, but was re-formed on 2 July 2009 to provide training to forward air controllers and to support Army Special Operations Command.

A Flight is composed of aircrew responsible for operating four Pilatus PC-21(F) Forward Air Control (FAC) variant aircraft.

[3] Selection to become a Combat Controller is open to any ADF member and involves completion of the 8-week CCT Intake Course providing preparatory ground skills training and to prepare volunteers for the Special Forces Entry Test.

[12] Volunteers need to pass the Special Forces Entry Test, complete the Commando Reinforcement Training Cycle, Joint Terminal Attack Controller, Aviation Meteorology, Assault Zone Reconnaissance and Air Weapons Delivery courses.

[5][13][14] After passing selection and completing nearly two years of training, the Combat Controller is issued with a grey beret featuring a Sykes-Fairbain (commando) dagger.

[9] C Flight delivers the ADF Joint Terminal Attack Controller (JTAC) course as well as the ongoing accreditation of graduates.

[15][16] The six-week JTAC course teaches planning, briefing, controlling and reporting of close air support (CAS).

[18][19] According to the unit war diary, Captain Andrew Lang took command of the squadron and its initial complement of one officer and 26 men on 25 October.

Operating Sopwith Camels and Snipes, it performed fighter sweeps, provided air support for the army, and raided German airstrips.

[22] Members of the unit included Captain Harry Cobby, the AFC's leading ace of the war, credited with destroying 29 aircraft and observation balloons, and Captain George Jones, who shot down seven aircraft and later served as the RAAF's Chief of the Air Staff for ten years.

4 Squadron was re-formed as a general reconnaissance unit at RAAF Station Richmond, New South Wales, on 3 May 1937, flying Hawker Demons before taking delivery of its first Avro Anson the following month.

Originally equipped with Demons and De Havilland Moths, it converted to CAC Wirraways in September and relocated to Canberra later that month.

4 Squadron deployed to Camden Airfield, where it flew anti-submarine patrols as well as army co-operation training sorties until redeploying to Queensland and then in November to New Guinea.

Until the end of the war the squadron operated in the army co-operation role, providing ground forces with artillery observation, reconnaissance and close air support.

[31] After completing training on its new aircraft, the squadron provided a firepower demonstration for cadets of the Royal Military College, Duntroon, during an exercise at Braidwood in September 1947.