central and northern bougainville

The capture of Pearl Ridge at the beginning of January, and the establishment of strong defensive positions there, had prevented any further enemy attack on Torokina from the east. For the next six months activity was limited to offensive patrols on the eastern side of the central range, to lower the morale of the enemy troops stationed there. In June pressure was increased. Forward enemy garrisons were attacked, and Australian outposts were established on the eastern side of the range. When the end of the war came, long-range patrols, operating from a temporary base on the lower reaches of the Wakuna River, were harassing enemy communications on the east coast in the Numa Numa area.

Operations in northern Bougainville were part of the responsibility of the 11th Brigade until June 1945, when it was relieved by the 23rd Brigade. Early in January a base was established at Amun, ten miles up the coast from Cape Moltke, and from there the advance was continued without opposition for another 20 miles to Puto. The first contact with the enemy in any strength was made on 17 January on the coastal track a mile south of Tsimba, at the mouth of the Genga River.

The Japanese had moved troops down from Buka, and from carefully prepared positions they hotly contested the Australians' efforts to reach the Genga. Artillery and air strikes were used to break down the enemy resistance, and by 9 February the south bank of the river was reached. From there a series of small outflanking movements forced the enemy to withdraw, and on 21 February the forward Australian troops reached the mouth of the Gillman River. The main axis of the advance was along the coastal trail, but the Japanese had established defensive positions, including artillery, on the ridges and foothills to the east and on a number of small islands lying off shore. These had to be dealt with, as they commanded the trail and helped considerably to slow up the Australians' progress.

A further series of operations, against determined opposition. resulted in the Japanese being cleared from the Soraken Peninsula. Then the Australians advanced to Pora Pora and Ratsua, on the western side of the base of the Bonis Peninsula. From there, early in May, a line was established to Ruri Bay, on the east coast, and the Japanese on Bonis were cut off from the rest of Bougainville.

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The line, about 10 miles long, was held at intervals by posts of company strength. Attempts were made to advance northward but they were unsuccessful. The enemy occupied the peninsula in strength and had developed strong defensive positions that could not be overcome with the forces available.

In July it was decided that the line was too thinly held to be effective, for the Japanese were becoming increasingly aggressive. Consequently, the company bases were withdrawn and concentrated at Bonis Plantation and Ruri Bay. From there, on either side of the peninsula's base, strong patrols were sent out to cover the escape routes to the south. By the end of July enemy activity south of their main defensive line had been reduced to a minimum as a result of these patrols, and this state of affairs lasted until hostilities ceased on 15 August.

A fourth theatre of war on Bougainville, in which the RNZAF was from time to time called upon to assist, was in the south-east. There, particularly in the Kieta area, the natives carried on their own private guerrilla war with the Japanese and in the course of the year caused them some hundreds of casualties.