 Japan's entry into the war on 7 December 1941, and the consequent perceived invasion threat to Australia, led to a further expansion of Moreton Bay's defences.Fort Bribie upgraded its two 6" gun emplacements in early 1942, and in June 1942, the Commander of the Allied Naval Forces in the Southwest Pacific Area requested as a matter of high priority that Moreton Bay be developed as a naval operating base.Later that year two American field guns were emplaced on Panama Mounts at Skirmish Point (Bribie Island Second World War Fortifications), at the south end of Bribie Island.