 Prior to the entry of Japan into World War II in early December 1941 it was the policy of Military Command in New South Wales to give priority to the fortification of the industrial areas of Newcastle, Sydney and Port Kembla.However, Japan's rapid advance and it's attack on Malaya and Pearl Harbor, saw the decision made that certain country areas also needed defensive measures in the event of an air attack, including Lithgow and Bathurst.In addition, bridges and roads were identified for destruction, road blocks and obstacles were erected in northern suburban areas of Sydney, tank traps were constructed and a variety of activities undertaken to prevent a land based enemy invasion reaching the inland areas.