I can add a little more to this story, my Uncle was in the Military at this time, and he and others where rushed all over Newcastle, my uncle ended up patrolling an area called scrubby creek which is near the Mt. Hutton area. He said that he had never been so scared in his life and every tree had a jap. in them which turned out to be possums, it was also rumoured that the sub. actually landed for a short while on nearby Redhead Beach, dont know how true cause all that generation have passed over..