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The Borneo campaign of 1945 was the last major Allied campaign in the South West Pacific Area during World War II to liberate the-Japanese held British Borneo and Dutch Borneo. In a series of amphibious assaults between 1 May and 21 July, the Australian I Corps, under Lieutenant General Leslie Morshead, attacked Imperial Japanese forces occupying the island. Allied naval and air forces, centred on the U.S. 7th Fleet under Admiral Thomas Kinkaid, the Australian First Tactical Air Force and the U.S. Thirteenth Air Force also played important roles in the campaign. They were resisted by Imperial Japanese Navy and Army forces in southern and eastern Borneo, under Vice-Admiral Michiaki Kamada, and in the north west by the Thirty-Seventh Army, led by Lieutenant-General Masao Baba.

Borneo campaign (1945)
Part of World War II
Borneo Campaign CMH.jpg
A map showing the progress of the Borneo campaign
Date1 May – 15 August 1945
Result Allied victory[1]

 United Kingdom

 United States

Commanders and leaders
United States Douglas MacArthur[2]
Australia Leslie Morshead
United States Thomas Kinkaid
Empire of Japan Michiaki Kamada
Empire of Japan Masao Baba
35,000 15,000
Casualties and losses
2,100 casualties[3] 4,700 casualties[4]


The plans for the Allied attacks were known collectively as Operation Oboe.[5] The invasion of Borneo was the second stage of Operation Montclair,[1] which was aimed at destroying Imperial Japanese forces in, and re-occupying the Dutch East Indies, Raj of Sarawak, Brunei, Labuan, British North Borneo and the southern Philippines.[5] Borneo in particular was considered at the time a strategic location for its natural resource; oil and rubber.[6]

The initial Allied plan comprised six stages: Operation Oboe 1 was to be an attack on Tarakan; Oboe 2 against Balikpapan; Oboe 3 against Banjarmasin; Oboe 4 against Surabaya or Batavia (Jakarta); Oboe 5 against the eastern Netherlands East Indies; and Oboe 6 against British North Borneo (Sabah). In the end only the operations against Tarakan, Balikpapan and British Borneo—at Labuan and Brunei Bay—took place.[7][8] Prior to the main landings in north Borneo the Allies undertook a series of reconnaissance operations, codenamed Agas and Semut.[9]

The campaign opened with Oboe 1 by a landing on the small island of Tarakan, off the north east coast on 1 May 1945 using Australian built MKIII folboats.[10] Small parties paddled in the Tarakan region to obtain useful information and observe the Djoeta oilfields prior to an invasion. On 29 May 1945, the Oboe 6 party, including Sergeant J Wong Sue, was inserted into Kimanis Bay, British North Borneo for close reconnoitreing work using a Hoehn military folboat deployed from a Catalina aircraft.[10]

On 10 June 1945, Oboe 6 subsequently followed with simultaneous assaults on the island of Labuan and the coast of Brunei in the north west of Borneo.[8] A week later, the Australians followed up with attacks on Japanese positions around Weston on the north-eastern part of Brunei Bay.[11][12] The attention of the Allies then switched back to the central east coast, with Oboe 2. The last major amphibious assault of World War II was at Balikpapan on 1 July 1945.[13] These operations ultimately constituted the last campaigns of Australian forces in the war against Japan.[14]



The Borneo campaign was criticised in Australia at the time and in subsequent years, as pointless or a "waste" of the lives of soldiers especially following the first operation in Tarakan.[15] Modern historians such as Max Hastings have said that attacking these forces, already cut off from Japan, was a waste of resources.

"Any rational strategic judgment would have left them to their own devices screened by token allied forces until their nation's defeat enforced their surrender".[16]

It has been argued that the campaign did, however, achieve a number of objectives, such as increasing the isolation of significant Japanese forces occupying the main part of the Dutch East Indies, capturing major oil supplies, and freeing Allied prisoners of war, who were being held in increasingly worse conditions in the Sandakan camp and Batu Lintang camp.[17][18]



  • Australian War Memorial (1968). Australia in the War of 1939-1945. Australian War Memorial.
  • Australian War Memorial London. "Borneo: The End in the Pacific, 1945 [The Battle in Brief]". Australian War Memorial, London.
  • Asagumo Shimbunsha (1966). 戦史叢書 [Senshi Sōsho] (in Japanese). 60. Asagumo Shimbunsha.
  • Converse, Allan (2011). Armies of Empire: The 9th Australian and 50th British Divisions in Battle 1939-1945. Cambridge University Press. ISBN 978-0-521-19480-8.
  • Dean, Peter J. (2015). Australia 1944-45: Victory in the Pacific. Cambridge University Press. ISBN 978-1-107-08346-2.
  • Dean, Peter J. (2018). MacArthur's Coalition: US and Australian Operations in the Southwest Pacific Area, 1942-1945. University Press of Kansas. ISBN 978-0-7006-2604-5.
  • Dennis, Peter (1995). The Oxford companion to Australian military history. Oxford University Press.
  • Great Britain. Ministry of Defence Navy (1995). War with Japan: The Advance to Japan. H.M. Stationery Office. ISBN 978-0-11-772821-9.
  • Hastings, Max (2007). Nemesis: The Battle for Japan, 1944-45. HarperPress. ISBN 978-0-00-726816-0.
  • Hastings, Tony. "A Wasted Effort? – The RAAF and the Battle for Tarakan - Part 1". Military History & Heritage Victoria.
  • Hoehn, John (2011). Commando Kayak. Hirschbooks. ISBN 978-3-033-01717-7.
  • Long, Gavin Merrick (1963). The Final Campaigns. Australian War Memorial.
  • Mikaberidze, Alexander (2018). Behind Barbed Wire: An Encyclopedia of Concentration and Prisoner-of-War Camps. ABC-CLIO. ISBN 978-1-4408-5762-1.
  • Ooi, Keat Gin (2010). The Japanese Occupation of Borneo, 1941-45. Routledge. ISBN 978-1-136-96309-4.
  • Ooi, Keat Gin (2002). "Prelude to Invasion: Covert Operations Before the Re-occupation of Northwest Borneo, 1944–45". Journal of the Australian War Memorial. Canberra: Australian War Memorial (37). ISSN 1327-0141. Retrieved 2 November 2014.
  • Pfennigwerth, Ian (2009). Royal Australian Navy & MacArthur. Rosenberg Publishing Pty, Limited. ISBN 978-1-922013-21-7.
  • Sandler, Stanley (2001). World War II in the Pacific: An Encyclopedia. Taylor & Francis. ISBN 978-0-8153-1883-5.
  • Tanaka, Yuki (2017). Hidden Horrors: Japanese War Crimes in World War II. Rowman & Littlefield Publishers. ISBN 978-1-5381-0270-1.

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