A number of Australian Empire Air Training Scheme squadrons were formed at Williamtown before proceeding overseas and No. 4 Operational Training Unit was located at Williamtown from October 1942 until the unit was disbanded in April 1944.
In 1983 the role of Williamtown was upgraded to a tactical fighter base in preparation of the replacement of the Mirages with 75 F/A-18 Hornets in 1989.