12 June 1942. Rabaul.
The casualties taken to capture of Rabaul had made the South Seas Detachment incapable of any further meaningful progress. It was decided to convert 36 Division, from 1st Army North China Area, to an ocean division. As it was the replacement for the South Seas Detachment, it was named the 5 South Seas Detachment under the command of Lieutenant General Izeki Mitsuru. The force was made up of three Regiments (222nd, 223rd 224th), with attached engineers, tanks and artillery.
The presence of strong Australian forces on New Guinea had made the Solomon Islands a more attractive direction for expansion of the Japanese defensive perimeter. Elements of the Special Naval Landing Force had carried out reconnaissance by force, finding little or no resistance. Among the places that had been earmarked for the construction of airfields was on Guadalcanal and seaplane bases on Shortland Island and Tulagi. The completion of the airfield at Lunga Point on Guadalcanal was imminent, and the seaplane bases were both operational.
Beyond the Solomons the severing of the connection between America and Australia was desirable. The New Hebrides, New Caledonia, Fiji and Samoa were all good places to cut the route, and therefore the American reinforcements going to Australia and New Zealand. In addition to the desire to cut the links between the USA and Australia, the islands of Naura and Ocean had good phosphate deposits, which were desirable natural resources.
The Army planners' concern of the possibility of an attack from the Soviet Union was looking less likely as the progress of the Germans. This gave the Imperial Army Headquarters some reason for optimism that such an attack remained unlikely, even with American support. More resources were earmarked for the Army in Thailand and Malaya, and General Homma’s successful campaign in the Philippines allowed for the Southern attack to continue.
The Imperial Japanese Navy were still looking for the decisive battle with the American fleet, and the increasing British Eastern Fleet. The attacks on New Caledonia, Fiji and Samoa would probably give the Americans no choice but to commit their surviving fleet units, and so allow the IJN to overwhelm them.
Once the link between America and Australia was cut, then finishing off the American, British, Dutch and Australian forces on the Malay barrier would be completed, and the natural resources of the area be available to strengthen the Japanese economy.
There had been a discussion about bringing the American fleet to battle at Midway, with a diversionary attack on the Aleutian Islands. The advantage of this FS Operation however was that it was much closer to the bases on Truk and Rabaul, and had the advantage of some land-based airpower to supplement the 1st Air Fleet.
Getting enough transport ships together to carry part of 36 Division had been one of the planning constraints, but Rabaul harbour was packed with both transports and escorts as the operation was about to get underway. The main carrier and battleship force was gathered at Truk, and would rendezvous with the invasion fleet at the appointed hour.
