Fremantle's secret fleet

In February 1942 Singapore, the last remnant of British colonial rule in Southeast Asia surrendered to Japanese forces. For the rest of World War 2 Fremantle became an important USA, British and Dutch submarine base. 170 American, British and Dutch submarines undertook 416 patrols from Fremantle. These patrols were essential – in the first few months of 1944 more Allied ships were sunk in the Indian Ocean than in the Atlantic Ocean.

Anti-submarine and anti-torpedo boom nets were placed across the entrance to Fremantle Harbour. There was a central gate opened by a winch on the North Mole, and two buildings were constructed on the western end of Victoria Quay for the naval boom defence operating unit.

Additionally in 1944 the highly classified Allied Research Bureau established a top secret base in Careening Bay, Garden Island for training crews in covert operations behind enemy lines, including the operation of midget submarines and submersibles.