Borneo campaign
On the 16th of December 1941, Japanese troops landed at Sarawak. A single battalion of British Indian troops fought a delaying action over several weeks. They damaged vital oil installations before retreating. On the 11th of January 1942, Japanese forces landed on the island of Tarakan. Parachute troops dropped on Celebes the following day. The small Dutch garrison destroyed some infrastructure before being overwhelmed. Between 80 and 100 Europeans were executed in Balikpapan as harsh reprisals followed the destruction of facilities.
The Imperial Japanese Army administered occupied British North Borneo while the Imperial Japanese Navy controlled Dutch Borneo. Garrison forces remained very small until mid-1944. Local populations faced severe hardship during this period. Large numbers of people on Tarakan were conscripted as labourers. Food became increasingly scarce for civilians. An open revolt by local Dayak tribesmen and ethnic Chinese began in October 1943. This Jesselton revolt was violently suppressed with hundreds executed. Many more died from diseases and starvation after Japanese policies became even more restrictive.
Plans for Allied attacks were known collectively as Operation Oboe. The invasion of Borneo formed the second stage of Operation Montclair. General Douglas MacArthur's South West Pacific Area headquarters developed planning in late 1944 and early 1945. Australian ground forces took primary responsibility for recapturing Borneo. The Australian I Corps had not engaged in combat for over a year prior to this assignment. Lieutenant-General Leslie Morshead commanded these forces directly under MacArthur rather than part of the Eighth Army.
The initial plan comprised six stages including operations against Tarakan, Balikpapan, Banjarmasin, Surabaya, eastern NEI, and British North Borneo. Only four locations saw actual landings: Tarakan, Labuan, North Borneo, and Balikpapan. General Thomas Blamey recommended against landing at Balikpapan believing it served no strategic purpose. The Australian Government agreed to provide forces only after MacArthur urged them. Reconnaissance operations codenamed Agas and Semut preceded main landings. These missions worked to arm, train, and organize local populations for guerrilla warfare against Japanese forces.
Oboe 1 opened with a landing on small island of Tarakan off north-east coast on the 1st of May 1945. Small parties of reconnaissance troops paddled into region using Australian-built MK III folboats. They observed Djoeta oilfields before invasion. Heavy aerial bombardment commenced the 12th of April by RAAF and US aircraft operating from Morotai Island and Philippines. Three days prior to assault, minesweepers cleared area of naval mines. Assault troops from 2/23rd and 2/48th Infantry Battalions came ashore under cover of strong naval barrage.
Initially they encountered no opposition before advancing north towards Tarakan town. Opposition around Lingkas Hill was overcome by end of first day. By the 5th of May the airfield was captured by Australians. Final major objective, Hill 90, secured on the 20th of June but small scale clashes continued afterwards. Airfield so heavily damaged it took eight weeks to repair. War essentially ended by that time. Historian Gavin Long believes invasion did not justify casualties suffered. Twenty-two five Australians killed and 669 wounded during operation. One thousand five hundred forty Japanese killed and 252 captured.
Oboe 6 began on the 10th of June with simultaneous assaults by 24th Brigade on island of Labuan and 20th Brigade on coast of Brunei. Troops were brought to shore by 727th Amphibian Tractor Battalion. Japanese forces held positions away from coast making landings unopposed. Town of Brunei secured on the 13th of June then brigade advanced along coast towards south-west. Objective was Miri-Lutong area. 2/17th Battalion moved by land while 2/13th Battalion made amphibious landing at Lutong on the 20th of June in LVT-4s.
Fighting on Labuan cost 24th Brigade 34 killed and 93 wounded. Australian soldiers counted 389 Japanese dead and took 11 prisoners. Heaviest fighting occurred 27/the 28th of June during Battle of Beaufort where more than 100 Japanese defenders were killed. After this engagement 24th Brigade undertook limited further advances pushing Japanese into hills. Clashes continued into August. On the 3rd of August Japanese attempted counterattack against position held by 2/28th Battalion. At least 11 Japanese killed for loss of one Australian. Operations involved substantial civil affairs effort assisting liberated civilian population.
Conventional operations accompanied guerrilla warfare campaign organized by Special Operations Australia. Two operations included Agas in British North Borneo and Semut in Sarawak. Five SOA parties inserted in North Borneo between March and July 1945. Agas 1 and 2 established networks of agents and guerrillas in north-western Borneo. Agas 4 and 5 landed on east coast achieving little results. Agas 3 party investigated Ranau area upon request from I Corps.
Over 100 Allied personnel inserted by air into Sarawak as part of Operation Semut from March 1945. Most personnel were Australian. Dayaks enthusiastically joined guerrilla groups led by small private armies. No. 200 Flight RAAF and Royal Australian Navy Snake-class junks played important roles inserting personnel and supplies. Guerrilla forces launched attacks to gain control interior while 9th Division focused coastal areas. They operated from patrol bases around Balai, Ridan and Marudi along Pandaruan and Limbang Rivers. Campaign highly successful with over 1,800 Japanese killed through guerrilla actions in north Borneo.
Allied attention switched back to central east coast for Oboe 2. Last major amphibious assault of World War II occurred at Balikpapan on the 1st of July 1945. Landing preceded heavy aerial bombardment over course of 20 days. Minesweepers worked to clear area for 15 days establishing safe lanes for invasion fleet. Three minesweepers lost during clearance operations inside range of Japanese coastal guns. Invasion fleet sailed from Morotai Island on the 26th of June arriving off Balikpapan on the 29th of June.
Landing area subjected to over 45,000 rounds preparatory fire from Australian US and Dutch warships supporting landing. Total 33,000 personnel assigned including 21,000 from Australian 7th Division under Major General Edward Milford. Initial assault undertaken by three infantry battalions: 2/10th left, 2/12th centre, 2/27th right. Troops landed wrong location due to smoke making navigation difficult but beachhead quickly established. Balikpapan town and port captured on the 3rd of July though mopping up continued into the 4th of July. Operations cost Australians 229 killed and 634 wounded while placing Japanese losses at 2,032 killed.
Australian personnel remained in Borneo until late 1945 restoring civilian administration overseeing reconstruction efforts. They supervised surrender of Japanese troops liberating former Allied prisoners held in camps around island. Claimed that forces near Beaufort encouraged local fighters massacre surrendered Japanese after war revenge for Sandakan Death Marches. Almost 6,000 Japanese reportedly killed though historian Ooi Keat Gin states no documentary evidence supports claims.
Historian Eustace Keogh called amphibious operations outstanding feature representing largest such operations Australians undertook during war. Casualties amounted about 2,100 Allied side while Japanese suffered about 4,700 casualties. Considerable number civilians killed or wounded including least 100 from pre-invasion bombardment Tarakan. Campaign criticized in Australia as pointless waste lives especially following first operation Tarakan. Historian Max Hastings argued attacking already cut-off forces was waste resources. Any rational strategic judgment would have left them to own devices screened token allied forces until nation defeat enforced surrender.
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Common questions
When did Japanese troops land at Sarawak during the Borneo campaign?
Japanese troops landed at Sarawak on the 16th of December 1941. A single battalion of British Indian troops fought a delaying action over several weeks before retreating.
Who commanded Australian ground forces in the Borneo campaign?
Lieutenant-General Leslie Morshead commanded Australian ground forces directly under General Douglas MacArthur. The Australian I Corps had not engaged in combat for over a year prior to this assignment.
What were the dates and locations of Operation Oboe landings in the Borneo campaign?
Operation Oboe included landings on Tarakan on the 1st of May 1945, Labuan and Brunei on the 10th of June 1945, and Balikpapan on the 1st of July 1945. Only four locations saw actual landings: Tarakan, Labuan, North Borneo, and Balikpapan.
How many Australians died during the Borneo campaign operations?
A total of approximately 2,100 Allied personnel died during the Borneo campaign operations. Specific figures include 225 Australians killed and 669 wounded during the Tarakan operation alone.
When did guerrilla warfare campaigns begin in Sarawak during the Borneo campaign?
Guerrilla warfare campaigns began in Sarawak from March 1945 as part of Operation Semut. Over 100 Allied personnel inserted by air into Sarawak with most personnel being Australian.