The Imperial Japanese force that had an interest in Papua and New Guinea was the Navy – the Army expressed little ambition in the area. Naval planning for a war against the US could be called a strategy of decreasing offensives. This conception was based in the premise that the Japanese Navy was aware of the inferiority of its fleet to the US fleet. There was no possibility that Japanese forces could cross the Pacific and occupy the US mainland. Consequently, in the event of war against the US, the Japanese Navy planned, through a series of measures, to gradually weaken the US Pacific fleet as it crossed the Pacific. It would then engage the US fleet in a decisive battle in the waters near Japan.
The extent of Japanese waters in the pre-war period (1940) where this decisive battle was planned to be fought ranged from the Marianas in the East, to the Marshall Islands in the North. Truk Atoll in the Caroline Islands had become the main advance base in the region for the Japanese Combined Fleet. The principal threat to the Combined Fleet base at Truk was from Australian-controlled Rabaul in the Bismarck Archipelago.
In August 1941, the Navy Department of Imperial Headquarters considered the occupation of the Bismarck Archipelago essential in the case of war with the US. The Navy strongly petitioned the Army to increase troops for this purpose. The Army, while recognising the need to occupy Rabaul, considered the deployment of troops to the region to be beyond the limits of its capability, and initially refused the request.
A compromise was, however, later reached between the Army and Navy. The Bismarck Archipelago was included in the region to be occupied in the Imperial Army Strategic Plan following the outbreak of war with the US, England and the Netherlands in November 1941. The South Seas Force (comprising a strengthened infantry regiment of approximately 5,000 men) was ordered to occupy Rabaul.
Japanese military interest:
Overview textRelated theme/s:
Japanese pre-war interest
