Queensland State Archives posted a photo:
Fort Lytton’s role in the Second World War was very different from previous times. It was now part of a much larger defence system. Between 1937 and 1943, four more coastal forts were built to defend Moreton Bay. These forts provided the outer defence to prevent enemy vessels from reaching the mouth of the Brisbane River, while Fort Lytton provided the inner defence.
The four outer forts were Fort Bribie and Fort Skirmish on Bribie Island, and Fort Cowan Cowan and Fort Rous on Moreton Island. Each of these forts was equipped with two six-inch guns, giving combined coverage to most of Moreton Bay. Also, the navy operated indicator loops and remote-controlled minefields in the deep water channels of Moreton Bay, giving them the potential to detect and destroy enemy vessels including the submerged submarines.
Description source:
Wikipedia
View the original record at the Queensland State Archives:
Item ID 2692229