Royal New Zealand Air Force
THE elimination of the Japanese defence network in the central Solomons opened the way for the final stage of the campaign, which was designed to secure bases from which Rabaul could be attacked from the east. General MacArthur's South-West Pacific forces were already preparing to land on the western part of New Britain and so bring Rabaul within easy striking distance from the west. As early as July 1943 the South Pacific Command had decided that an attack should be made on Bougainville. In the following months the original plan, which had visualised a frontal assault on the bases in the Kahili area, was revised several times. In its final form the operation took the form of a landing at Cape Torokina, to the north of Empress Augusta Bay, half-way up the western side of the island. The area selected for the beach-head comprised a natural defensive region of about six miles by eight. It possessed a number of disadvantages in that the low, swampy, timbered coast had only limited protection from onshore winds, and there was no satisfactory anchorage for large vessels. The only communications in the area were a meagre network of foot trails. Moreover, some of the native tribes in the locality were known to favour the enemy. On the other hand enemy defences were reported to be weak, and the ground was suitable for building airstrips. Strategically, too, Empress Augusta Bay was almost equidistant between the enemy installations at Buka in the north and the Shortland area in the south, and lay astride the enemy communications with Rabaul.
Preparatory to the main operations the Treasury Islands, immediately to the south of Bougainville, were to be seized to provide a base for further operations and to protect the flank of forces moving northwards to Empress Augusta Bay. To confuse the enemy as to where the major blow was to fall, a diversionary landing was to be made on Choiseul five days beforehand by the 2nd Marine Parachute Battalion.
In preparation for the attack on Bougainville, Allied air forces were moved up to the New Georgia area and additional airfields were built on New Georgia and Vella Lavella and existing ones improved. Early in September COMAIRSOPAC had ordered that two page 200 RNZAF fighter squadrons with their ground staffs should move from Guadalcanal to Munda when No. 3 field was ready for operations in October. This plan was not, in fact, carried out as the New Zealand squadrons eventually went to Ondonga instead of Munda. Early in October it was proposed that they should be based at Segi. This was opposed by No. 1 (Islands) Group as Segi had only short runways, the P40s had poor brakes, and if they operated from there a large number of accidents could be expected. No definite decision was reached until 11 October when COMAIRSOLS informed the Group that the squadrons and their ground units were to move to Ondonga.