The French firm of Avions Marcel Dassault were among the leading innovators in high performance military aircraft design in the 1950s & 1960s. Their Mirage III delta-wing design first flown in November 1956 became the first western aircraft to reach Mach 2 in level flight. Production versions were sold to many foreign air forces. The Mirage IIIO was selected to replace the CAC Sabre in RAAF service in December 1960. The Government Aircraft Factory was the prime contractor for local production with the Commonwealth Aircraft Corporation building the SNECMA Atar 9c jet engine, wings, fin and rudder.
The first aircraft to be delivered to the RAAF were French-built with the first locally built examples to be delivered in 1964. The project suffered from delays and skills shortages and additional fuselages had to be purchased from France. The two-seat IIID was also purchased for the RAAF with fuselages being supplied from France. A total of 100 Mirage IIIO aircraft were received by the RAAF by 1968 of which 98 were locally assembled or built. The Mirage performed successfully and remained in service as the RAAF's primary fighter until replaced by the F/A-18 Hornet in the late 1980s. Most of the surviving aircraft were sold to Pakistan after a period of storage at Woomera in South Australia.