Bougainville campaign, fought during the
Pacific war from November 1943 to August 1945 on this Pacific island when US and then Australian troops tried to clear the island of its Japanese garrison. Bougainville, 200 km. (125 mi.) long, was the largest of the
Solomons group (see Map 83) and part of the Australian mandate of North-East New Guinea.
With successes in the
New Guinea and
New Georgia campaigns US Pacific forces began closing in on
Rabaul, the main Japanese base in the area. Bougainville was the last Japanese bastion between it and
Admiral Halsey's land forces advancing up the Solomons, and elements of Lt-General Hyakutake Haruyoshi's Seventeenth Army were therefore rushed to reinforce it. But most of his 37,500 men were sent to Buin at its southern end, or to various offshore islands, so when the 3rd US Marine Division landed at Empress Augusta Bay on 1 November 1943, after the 3rd New Zealand Division had seized the nearby Treasury Islands, it met only light opposition. A defensive perimeter was quickly established and work on airstrips begun, but the initial fighting for the beachhead was in the air and at sea. In the battle of Empress Augusta Bay, fought before dawn on 2 November, the US Navy's Task Force 39 sank a cruiser and a destroyer of Vice-Admiral Omori Sentaro's Eighth Fleet; while Lt-General Kenney's Fifth USAAF bombed Japanese airfields, and fought off Japanese air attacks on TF39 and on the beachhead. However, by far the most dangerous threat to the American campaign was the appearance of
Vice-Admiral Kurita's powerful task force at Rabaul. Halsey's only option to avert disaster was to attack Kurita before he left Rabaul and, in what he later called his ‘most desperate emergency’, Halsey sent his two-carrier task force within range of Japanese air power. It was a gamble—he expected to lose the carriers—but, protected by land-based aircraft, both remained untouched while their aircraft wrought such damage that Kurita withdrew to
Truk. Then, aided by the completed airstrips on Bougainville, further Allied bombing raids soon forced the complete withdrawal of Japanese air and naval units from Rabaul.
With Rabaul neutralized the Americans quickly built up their forces on Bougainville. By 15 December 1943, when Maj-General Oscar Griswold and his 14th Corps HQ took command, they had defeated several counter-attacks and extended their perimeter, and by 9 March 1944, the day Hyakutake launched a full-scale offensive, Griswold commanded 62,000 men. Though Hyakutake broke through at some points, he lost more than 5,000 men killed and on 27 March he withdrew. After Griswold had further enlarged his perimeter, a virtual truce ensued until 2nd Australian Corps under Lt-General Stanley Savige, which completed relieving the Americans in December 1944, started their own offensive. The wisdom of doing so was later seriously questioned in Australia, but the Allies had mistakenly estimated the strength of the Japanese to be between 12,000 and 25,000, when in fact they then numbered about 40,000. However, Pearl Ridge in the island's centre was captured and one brigade was able to push northwards to contain the Japanese in the Bonis peninsula. But when 3rd Division moved southwards down the west coast towards Buin the Japanese resisted fiercely, and mounted several determined counter-attacks, particularly in the area of Slater's Knoll. But by the time Japan surrendered they had been confined to an area about 48 km. by 24 km. (30 mi. by 15 mi.).
Australian casualties were 516 dead and 1,572 wounded during Savige's offensive. About 8,500 Japanese were killed during the course of it, 9,800 died of disease (see
medicine), and 23,571 surrendered.
