Borneo Campaign
Last major Allied offensive in the South West Pacific
1 May - 15 August 1945
author Paul Boșcu, February 2019
During the last stages of the Pacific War, Australian forces organized a series of landings on the island of Borneo. The goal of the campaign was the liberation of the island from Japanese hands.
The Borneo campaign was the last major Allied offensive in the South West Pacific during the Second World War. In a series of amphibious landings, Australian troops attacked the island. The goal of the campaign was to defeat the Japanese forces on Borneo and thus retake the Dutch and British possessions on the island.

In early 1945, the Americans asked the Australians to plan a series of landings on Borneo, an island divided into four sovereignties: two Dutch, two British. Air fields, oil fields and refineries gave the island added luster as an objective. Yet it never seemed plausible that these could be made serviceable in time to assist the Allied war effort. The American blockade already ensured that Borneo’s oil was doing little good to the Japanese. The view was widely held that the only purpose of the operation was to keep other Allied forces off America’s pitch for the last round of the Pacific War.

None of Borneo’s inhabitants had encountered within living memory such a large-scale conflict, where fast flying airplanes dropped devastating bombs, cannons from offshore ships bombarded the coast, and well-armed soldiers stormed the beaches. It was an unimaginable scenario unheard and unseen by anyone there before.

The Japanese military occupation of Borneo, a period of about three years and eight months, beginning in 1942, was an unsettling time. Daily life in occupied Borneo became increasingly stressful. As the occupation lengthened, the situation worsened. Acute shortages affected practically all items, from soap to rice to cloth; everything seemed to disappear from the shelves of once abundantly stocked Chinese shophouses in the bazaar. Having less food on the table was tolerable, but being slapped for failing to bow to the Japanese sentry was humiliating. The Japanese occupation not only had a dramatic impact but also brought about serious and radical developments in its aftermath.

Prices of goods, especially rice and other foodstuffs, began to increase, and more and more of the Japanese-issued paper currency had to be transacted for a bowl of beehoon (rice vermicelli) or a small bottle of cooking oil. Indigenous peoples reverted to their traditional ways, for example in fire-lighting methods, for want of matches.

Although the occupation was only a brief interval, it was a significant catalyst for change that manifested itself during the postwar period. By the late 1940s, all territories across Borneo, with the notable exception of Brunei, had undergone changes in political status and governance.

Worse still was the fear that one’s loved ones or neighbors might be taken away by the Kempeitai, the Japanese secret military police. There was a climate of uncertainty, that someone close by might be the next victim. Stories of horrific, inhumane treatment at the hands of the Kempeitai were revealed as unbelievably true when those who survived told of the tortures.

Overall among the peoples of Borneo there was heightened and accentuated ethnic consciousness, communal identity and concern over parochial interests and rights concerning one another. Armed with this awareness, there were different courses of action taken by the inhabitants of the various territories. The multi-ethnic population of Sarawak and North Borneo together with those in Brunei decided on continuity with their pre-war British protector. Brunei continued as a British protectorate while Sarawak and North Borneo converted into British Crown Colonies.

The diverse peoples of Kalimantan decided on change rather than continuity after the war. Although some groups, for instance the Dayaks, worked with the Dutch in a federalist framework, the majority embraced the Republican cause and rejected their former less than benign colonial masters. For better or worse the peoples of Kalimantan opted for change.

The landings in the Dutch East Indies, primarily on Borneo, grew out of discussions between the Americans and Australians. The Australian army had replaced American divisions containing the bypassed Japanese forces in the Southwest Pacific. The Japanese armies on New Guinea, Bougainville and New Britain presented no major threat; but the question of dealing with their soldiers remained. Thus the Allied Supreme Commander in the Pacific, General Douglas MacArthur, supported an invasion on Borneo, codenamed Operation Oboe.

MacArthur was at best lukewarm about the justification for these offensives, but he enthusiastically ordered the 1st Australian Corps, under Lieutenant-General Sir Leslie Morshead, to conduct operations in Borneo.

Borneo also attracted Allied attention as the site of the strongest resistance movement against Japanese occupation in the East Indies, carried out by a union of Chinese refugees, Dyak tribesmen and Allied soldiers who had managed to go into hiding during the 1942 occupation.

Australian-American relations were at times strained. MacArthur’s ambitions, especially his push for the re-taking of the Philippines, together with his haughty personality, were no match for Blamey’s unobtrusive and even pedestrian ways. MacArthur wanted the South West Pacific to be wholly an American theater of operation, and all victories to be to his personal credit, despite having an ally in Australia. Australian Prime Minister John Curtin had to continually insist that Australian forces be given a major role in the Pacific theater. Finally the reconquest of Borneo was assigned to them with US naval support.

Planning was undertaken by MacArthur’s staff at South West Pacific GHQ although Australian troops were the main forces in executing the operations. Oboe was the second phase of the Montclair plan that sought the re-occupation of Japanese-occupied territories in the South West Pacific. The Oboe phase when launched was expected to witness the reconquest of Borneo and the destruction of Japanese forces in the occupied Netherlands East Indies, including the seizure of Java.

Altogether there were six Oboe operations that were conceived in February 1945, but only three were subsequently executed: OBOE I– Tarakan, then OBOE VI– Brunei Bay and Labuan, and finally OBOE II– Balikpapan.

In principle, the re-taking of Borneo was agreed at the second Quebec conference of September 1944. The Bornean oil fields were to be secured for the British Pacific fleet that would join the Americans in the push for the Japanese home islands. Despite the Quebec decision and also Borneo’s strategic position for the re-conquest of Malaya and Java, the Allied Pacific strategy dictated by MacArthur appeared to be the Philippines. In this scenario Borneo appeared inconsequential; logistically its oil was too far away to aid the forces heading straight to Imperial Japan. Hence British and Australian military circles were having reservations as to the necessity of Borneo. But when Blamey voiced Australian concerns and suggested that the Borneo operations be shelved, MacArthur swiftly rejected such a proposal.

MacArthur played on the fact that the entire chain of command had already agreed in the reconquest of Borneo: ‘The Borneo campaign ... has been ordered by the Joint Chiefs of Staff who are charged by the Combined Chiefs of Staff with the responsibility for strategy in the Pacific ... Withdrawal would disorganize completely not only the immediate plan but also the strategic plan of the Joint Chiefs of Staff.’

Though reluctantly approved by Washington and Canberra, one of these landings, that at Balikpapan on the east coast of Borneo, was originally the subject of a controversy between MacArthur and the Australian government. Australian General Thomas Blarney was now more wary and he opposed the landing at Balikpapan. MacArthur warned the Australian government that to cancel the operation would disorganize Allied strategic plans; the government approved the landing. In truth, MacArthur wanted to show the Dutch government that he had attempted to recover part of its territory.

The first landing began with the seizure of Tarakan. Next, the Australians landed on Labuan Island and at Brunei. The landing at Balikpapan was the last amphibious operation of the war. The Australians lost fewer than 600 killed, but Japan did not surrender one minute earlier as a result.

The Australians, with Allied air and naval support, made their first landing on Borneo and continued with amphibious envelopments until the war’s end. Guerrilla units urged prompt action in Borneo because they knew the Japanese planned to kill Australian prisoners of war (POWs) and civilian internees. In marching their POWs to new sites, the Japanese killed more than 3,500 POWs and civilian internees on Borneo and Ambon Island before Allied special forces could rescue them.

Tarakan was garrisoned by 1,800 Japanese, and possessed an airfield thought likely to be useful for Allied operations on the mainland. The naval bombardment prior to troop landings and the fact that the bulk of the Japanese forces were inland at their headquarters area known as Fukukaku resulted in unopposed landing at the beaches. By the first day the Australians managed to advance two kilometres inland without heavy resistance. Rugged fighting followed. By the end of July, three hundred Japanese remained at large on Tarakan. The prized airfield proved beyond repair.

The Australians landed in Brunei Bay and secured the immediate coastal area. Phrases such as ‘meager opposition’, ‘slight resistance’, or ‘no serious opposition’ peppered the report of field operations. A notable exception was the experience of an infantry unit on Labuan, which ‘encountered strong enemy positions in the rough country between the airfield and swamp to the west.’ It was after 11 days of hard fighting that this stretch of territory was finally secured.

Meanwhile Victory in Europe was being celebrated with the surrender of the Wehrmacht and Germany. But in the Pacific, victory did not appear imminent. In a radio broadcast to the British public, Churchill reminded them of the Pacific War: ‘We must not forget that beyond all lurks Japan, harassed and failing but still a nation of a hundred millions, for whose warriors death has no terrors...’

After Brunei Bay the Australians carried out the last significant amphibious landing of the war at the Dutch oil port of Balikpapan, in the southeast of Dutch Borneo. The targets were Balikpapan’s refinery and port and its two airfields. Minesweeping and underwater demolition operations were carried out under cover of naval bombardment of enemy shore positions. Apart from enemy fire on landing crafts, which inflicted little damage, there was little opposition of the landing troops on the beaches.

Over the course of a week after the landings at Balikpapan, the Australians secured twenty miles of coastal territory around the port, leaving special forces and guerrillas to hunt Japanese through the inland wilderness. This was the Pacific War’s last large-scale operation, and the AIF’s largest amphibious operation.

The Australian Army lost 7,384 dead fighting the Japanese in the Second World War. This was fewer of the nation’s warriors than died as prisoners having been captured in Malaya and at Singapore in 1942. For a people whose soldiers, sailors and airmen won such admiration in other theaters, it was a tragedy that in their own hemisphere the wartime experience was poisoned by domestic strife and battlefield frustration.

British Prime Minister Winston Churchill bore a significant responsibility for his cavalier treatment of a nation which he continued to perceive as a colony, and for whose domestic difficulties he had no sympathy. Whatever the mitigating circumstances, however, it seemed perverse that, having won so much honor far away in the Mediterranean, Australia’s share of the Pacific War ended in rancor and anticlimax.

When the Japanese surrendered at Borneo, it took another month for the Australian 9th Division that had landed at Brunei Bay in June to be able to effectively assume control of Sarawak and former British North Borneo. Apart from a few remaining isolated units of the Japanese army in the interior that required mopping-up operations to disarm them, the military operational phase had ended. The last Japanese unit, the Fujino Force that had retreated inland to the Upper Trusan in Sarawak’s northeast, finally surrendered on 8 November, three months after Japan officially surrendered to the Allied forces.