|Borneo campaign (1945)|
|Part of World War II|
Australian troops advancing towards Brunei
|Commanders and leaders|
|Casualties and losses|
|2,100 casualties||4,700 casualties|
The Borneo campaign of 1945 was the last major Allied campaign in the South West Pacific Area during World War II to liberate Japanese-held British Borneo and Dutch Borneo. Designated collectively as Operation Oboe, a series of amphibious assaults between 1 May and 21 July were conducted by the Australian I Corps, under Lieutenant-General Leslie Morshead, against Imperial Japanese forces who had been occupying the island since late 1941 – early 1942. The main Japanese formation on the island was the Thirty-Seventh Army under Lieutenant-General Masao Baba, while the naval garrison was commanded by Vice-Admiral Michiaki Kamada. The Australian ground forces were supported by US and other Allied air and naval forces, with the US providing the bulk of the shipping and logistic support necessary to conduct the operation. The campaign was initially planned to involve six stages, but eventually landings were undertaken at four locations: Tarakan, Labuan, North Borneo and Balikpapan. Guerilla operations were also carried out by Dayak tribesmen and small numbers of Allied personnel in the interior of the island. While major combat operations were concluded by mid-July, mopping-up operations continued throughout Borneo until the end of the war in August. Initially intended to secure vital airfields and port facilities to support future operations, preparatory bombardment resulted in heavy damage to the island's infrastructure, including its oil production facilities. As a result, the strategic benefits the Allies gained from the campaign were negligible.
The Allies of World War II, called the United Nations from the 1 January 1942 declaration, were the countries that together opposed the Axis powers during the Second World War (1939–1945). The Allies promoted the alliance as a means to control German, Japanese and Italian aggression.
World War II, also known as the Second World War, was a global war that lasted from 1939 to 1945. The vast majority of the world's countries—including all the great powers—eventually formed two opposing military alliances: the Allies and the Axis. A state of total war emerged, directly involving more than 100 million people from more than 30 countries. The major participants threw their entire economic, industrial, and scientific capabilities behind the war effort, blurring the distinction between civilian and military resources. World War II was the deadliest conflict in human history, marked by 70 to 85 million fatalities, most of whom were civilians in the Soviet Union and China. It included massacres, the genocide of the Holocaust, strategic bombing, premeditated death from starvation and disease, and the only use of nuclear weapons in war.
Before the outbreak of World War II in the Pacific, the island of Borneo was divided into five territories. Four of the territories were in the north and under British control – Sarawak, Brunei, Labuan, an island, and British North Borneo; while the remainder, and bulk, of the island, was under the jurisdiction of the Dutch East Indies.
Prior to World War II, Borneo was divided between British Borneo in the north of the island and Dutch Borneo in the south; the later formed part of the Netherlands East Indies (NEI). As of 1941, the island's population was estimated to be 3 million. The great majority lived in small villages, with Borneo having less than a dozen towns. Borneo has a tropical climate and was mainly covered by dense jungle at the time of World War II. Most of the coastline was lined with mangroves or swamps.
British Borneo comprised the four northern parts of the island of Borneo, which are now the country of Brunei, two Malaysian states of Sabah and Sarawak, and the Malaysian territory of Labuan. During the British colonial rule before World War II, Sarawak was known as the Raj of Sarawak (1841–1946), Sabah was known as North Borneo (1881–1946), and Labuan was known as the Crown Colony of Labuan (1848–1946). Between World War II and their independence from Britain, Sarawak became the Crown Colony of Sarawak (1946–1963) whereas Sabah and Labuan combined to form the Crown Colony of North Borneo (1946–1963). The Kingdom of Brunei (1888/1906-1984) was a protectorate of the United Kingdom since the 1888/1906 Protectorate Agreement, and was known as British Protectorate State of Brunei.
Kalimantan is the Indonesian portion of the island of Borneo. It comprises 73% of the island's area. The non-Indonesian parts of Borneo are Brunei and East Malaysia. In Indonesia, "Kalimantan" refers to the whole island of Borneo. In 2019, the Indonesian President Joko Widodo proposed that Indonesia's capital be moved to Kalimantan.
The Dutch East Indies was a Dutch colony consisting of what is now Indonesia. It was formed from the nationalised colonies of the Dutch East India Company, which came under the administration of the Dutch government in 1800.
Borneo was strategically important during World War II. The European colonisers had developed oil fields and their holdings exported other raw materials. The island's location was also significant, as it sat across the main sea routes between north Asia, Malaya and the NEI. Despite this, Borneo was under-developed, and had few roads and only a single railroad. Most travel was by watercraft or narrow paths. The British and Dutch also stationed only small military forces in Borneo to protect their holdings.
Borneo was rapidly conquered by the Japanese in the opening weeks of the Pacific War during the Japanese occupation of Borneo. The purpose of this operation was to capture the oilfields and guard the flanks of advances into Malaya and the NEI.Japanese troops landed at Sarawak on 16 December 1941, where a single battalion of British Indian troops fought a delaying action over several weeks, damaging vital oil installations. Meanwhile, on 11 January 1942, Japanese troops landed on the island of Tarakan, while parachute troops carried out a drop on the Celebes the following day; the small Dutch garrison managed to destroy some of the infrastructure before eventually being overwhelmed. The destruction of these facilities led to harsh reprisals against civilians, particularly at Balikpapan where between 80 and 100 Europeans were executed.
The Pacific War, sometimes called the Asia–Pacific War, was the theater of World War II that was fought in the Pacific and Asia. It was fought over a vast area that included the Pacific Ocean theater, the South West Pacific theater, the South-East Asian theater, the Second Sino-Japanese War, and the Soviet–Japanese War.
Sarawak is a state of Malaysia. The largest among the 13 states, with an area almost equal to that of Peninsular Malaysia, Sarawak is located in northwest Borneo Island, and is bordered by the Malaysian state of Sabah to the northeast, Kalimantan to the south, and Brunei in the north. The capital city, Kuching, is the largest city in Sarawak, the economic centre of the state, and the seat of the Sarawak state government. Other cities and towns in Sarawak include Miri, Sibu, and Bintulu. As of the 2015 census, the population of Sarawak was 2,636,000. Sarawak has an equatorial climate with tropical rainforests and abundant animal and plant species. It has several prominent cave systems at Gunung Mulu National Park. Rajang River is the longest river in Malaysia; Bakun Dam, one of the largest dams in Southeast Asia, is located on one of its tributaries, the Balui River. Mount Murud is the highest point in Sarawak.
A battalion is a military unit. The use of the term "battalion" varies by nationality and branch of service. Typically a battalion consists of 300 to 800 soldiers and is divided into a number of companies. A battalion is typically commanded by a lieutenant colonel. In some countries, the word "battalion" is associated with the infantry.
In the aftermath, the Imperial Japanese Army (IJA) administered the occupied British North Borneo and the Imperial Japanese Navy (IJN) was responsible for Dutch Borneo. The garrison forces on the island were very small until mid-1944.During the occupation, the local population was subjected to harsh treatment. For example, on Tarakan large numbers of people were conscripted as labourers, the economy was disrupted, and food became increasingly scarce. In late October 1943, an open revolt by local Dayak tribesmen and ethnic Chinese began which was violently suppressed with hundreds being executed. In the aftermath, many more died from diseases and starvation as Japanese policies became even more restrictive on the local population. Japanese forces conducted a number of other massacres during their occupation of Borneo.
The Imperial Japanese Army was the official ground-based armed force of the Empire of Japan from 1868 to 1945. It was controlled by the Imperial Japanese Army General Staff Office and the Ministry of the Army, both of which were nominally subordinate to the Emperor of Japan as supreme commander of the army and the navy. Later an Inspectorate General of Aviation became the third agency with oversight of the army. During wartime or national emergencies, the nominal command functions of the emperor would be centralized in an Imperial General Headquarters (IGHQ), an ad-hoc body consisting of the chief and vice chief of the Army General Staff, the Minister of the Army, the chief and vice chief of the Naval General Staff, the Inspector General of Aviation, and the Inspector General of Military Training.
The Imperial Japanese Navy was the navy of the Empire of Japan from 1868 until 1945, when it was dissolved following Japan's surrender in World War II. The Japan Maritime Self-Defense Force (JMSDF) was formed after the dissolution of the IJN.
The Dayak or Dyak or Dayuh are the native people of Borneo. It is a loose term for over 200 riverine and hill-dwelling ethnic subgroups, located principally in the central and southern interior of Borneo, each with its own dialect, customs, laws, territory and culture, although common distinguishing traits are readily identifiable. Dayak languages are categorised as part of the Austronesian languages in Asia. The Dayak were animist in belief; however, many converted to Islam and since the 19th century there has been mass conversion to Christianity. Today most Dayak still follow their ancient animistic traditions, but often state to belong to one of the 6 recognized religions in Indonesia.
The plans for the Allied attacks were known collectively as Operation Oboe.The invasion of Borneo was the second stage of Operation Montclair, which was aimed at destroying Imperial Japanese forces in, and re-occupying the NEI, Raj of Sarawak, Brunei, the colonies of Labuan and British North Borneo, and the southern Philippines. Borneo in particular was considered at the time a strategic location for its natural resource; oil and rubber. Tarakan was also seen to offer a forward airbase to support future operations in the region, while Brunei Bay was intended to be used as naval base. Planning for the operation began in late 1944 and early 1945 through the General Headquarters of General Douglas MacArthur's South West Pacific Area. As a result of the commitment of US forces to the recapture of the Philippines, the task of recapturing Borneo was allocated primarily to Australian ground forces. By this time the Australian I Corps, the Australian Army's main striking force, had not engaged in combat for over a year. The corps had been assigned to MacArthur, but he had chosen to not use it in the Philippines despite the Australian Government pressing for this.
Operation Montclair was a military operation during the Second World War. The final version of the outline plan originally called Operation Princeton, it outlined plans to recapture the Visayas and Mindanao in the Philippines, Borneo and the Dutch East Indies.
The Raj of Sarawak, also State of Sarawak, was an independent state, and later a British protectorate, located in the northwestern part of the island of Borneo. It was established as an independent state from a series of land concessions acquired by an Englishman, James Brooke, from the Sultanate of Brunei. Sarawak received recognition as an independent state from the United States in 1850, and from the United Kingdom in 1864.
Brunei, officially the Nation of Brunei, the Abode of Peace, is a country located on the north coast of the island of Borneo in Southeast Asia. Apart from its coastline with the South China Sea, the country is completely surrounded by the insular Malaysian state of Sarawak. It is separated into two parts by the Sarawak district of Limbang. Brunei is the only sovereign state completely on the island of Borneo; the remainder of the island's territory is divided between the nations of Malaysia and Indonesia. Brunei's population was 428,963 in 2018.
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 the capital of the NEI, Batavia (modern-day Jakarta); Oboe 5 against the eastern NEI; and Oboe 6 against British North Borneo (Sabah). In the end only the operations against Tarakan, Balikpapan and British North Borneo – at Labuan and Brunei Bay – took place.These operations ultimately constituted the last campaigns of Australian forces in the war against Japan. In the planning phase the commander of the Australian Military Forces, General Thomas Blamey recommended against the landing at Balikpapan, believing that it would serve no strategic purpose. After much consideration, the Australian Government agreed to provide forces for this operation at MacArthur's urging. Blamey was able to frustrate MacArthur's plans for Australian troops to make follow-on landings in Java by convincing Prime Minister John Curtin to withhold the 6th Division. Prior to the main landings in British North Borneo the Allies undertook a series of reconnaissance operations, codenamed Agas (northern Borneo) and Semut (Sarawak); these operations also worked to arm, train and organise the local population to under take guerilla warfare against the Japanese to support conventional operations.
The Japanese military began to prepare for the defence of Borneo from mid-1944, as Allied forces rapidly advanced towards the island. IJA reinforcements were allocated to Borneo, but did not arrive until between September and November that year.In late 1944 the Japanese command judged that Australian forces were likely to attack the Brunei area and then capture the west coast of Borneo as part of a campaign aimed at liberating Singapore. Accordingly, most of the IJA units in north-eastern Borneo were ordered to move overland to the west coast; this required them to undertake gruelling marches over rugged terrain. Two other battalions were transferred from north-eastern Borneo by sea to south Borneo between February and March 1945. After United States forces liberated key areas of the Philippines, which cut the rest of South-East Asia off from Japan, on 27 January 1945 the IJA's General Staff ordered the forces in this area to defend the territory they held and not expect reinforcements.
The main Allied ground forces assigned to the campaign came from the Australian I Corps, under Lieutenant-General Leslie Morshead. The main elements of this force consisted of two infantry divisions: the 7th and 9th. For the operation, the Australian corps was assigned as a task force directly under MacArthur's command rather than as part of the Eighth Army, which was controlling operations in the Philippines.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. A small number of Dutch personnel also took part in the operations. Over 74,000 Allied troops were assigned to the initial landings of the campaign. The bulk of the logistic support was provided by the US, particularly provision of the shipping that was required to transport the vast amounts of troops, stores and equipment required for the operation.
Allied forces were resisted by IJN and IJA 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, which was headquartered in Jesselton. The main elements of the Thirty-Seventh Army were the 56th Independent Mixed Brigade (northern Borneo), 71st Independent Mixed Brigade (southern Borneo) and 25th Independent Mixed Regiment; these units had been raised in Japan during the second half of 1944 and arrived in Borneo late that year. The IJN's 2nd Naval Guard Force was also stationed in Borneo. Allied intelligence assessed that there were about 32,000 Japanese troops in Borneo, with 15,000 of these being combat troops. Most of the units which had been ordered from north-eastern Borneo to the west coast were still in transit when the Australian landings began and had been greatly weakened by the difficult conditions experienced during their cross-island march. The transfers left only single battalions in place at Tarakan and Balikpapan. Japanese air power in the region, except in Java and Sumatra, was ineffective.
The campaign opened with Oboe 1, which consisted of a landing on the small island of Tarakan, off the north-east coast on 1 May 1945. This operation was undertaken to capture the island's airstrip so that it could be used to support the subsequent landings on the mainland of Borneo.Using Australian-built MK III folboats, small parties of reconnaissance troops paddled into the Tarakan region to obtain useful information and observe the Djoeta oilfields prior to an invasion.
The landing on Tarakan was assigned to the heavily reinforced 26th Brigade, under the command of Brigadier David Whitehead. This brigade's three infantry battalions were augmented with two battalions of pioneers as well as commandos and engineers. American amphibious engineers and a Dutch infantry company (made up of soldiers from Ambon Island) and civil affairs unit were also placed under Whitehead's command. Overall, the 26th Brigade had a strength of just under 12,000 troops.The Australian assault was preceded by a heavy aerial bombardment commencing 12 April, and undertaken by RAAF and US aircraft operating from Morotai Island and the Philippines; these aircraft interdicted Japanese shipping, attacked airfields, reduced obstacles around the landing beaches and suppressed artillery and defensive positions; in addition, a preliminary landing was undertaken on Sadau Island by a group of commandos and an artillery battery. Naval assets assigned to provide fire support during the operation include three cruisers, seven destroyers and several landing craft fitted with rockets and mortars. Three days prior to the assault, a force of minesweepers worked to clear the area of naval mines.
During the main landing, the battery on Sadau Island provided fire support to the Australian engineers who were landed at Lingkas to clear obstacles on the landing beaches. Assault troops from the 2/23rd and 2/48th Infantry Battalions came ashore under the cover of a strong naval barrage. Initially, they encountered no opposition before they began to advance north towards Tarakan town. Opposition around Lingkas Hill was overcome and by the end of the first day a strong beachhead had been established. The brigade reserve, the 2/24th Infantry Battalion, was landed the next day as the advance towards the airfield continued. Japanese resistance grew, and the advance was hindered by large numbers of mines and booby traps, which had to be cleared by engineers and pioneers; however, finally, on 5 May the airfield was captured by the Australians. Meanwhile, operations continued into June as isolated pockets of Japanese resisted the Australians in tunnels and on high features across the island. The final major objective, Hill 90, was secured on 20 June, but small scale clashes continued after this. Ultimately, the airfield was so heavily damaged that it took eight weeks to repair, by which time the war was essentially over.As a result, most historians, including the Australian official historian Gavin Long, believe that the invasion of Tarakan did not justify the casualties suffered by the Allied forces; these included 225 Australians killed and 669 wounded. Japanese casualties were even heavier, with 1,540 being killed and 252 captured.
The landings in north-west Borneo had several goals. These included securing the Brunei Bay area for use as a naval base and capturing oil and rubber facilities. A total of 29,000 personnel were assigned to the operation, just over 1,000 of these were US and British personnel, while the rest were Australian. Almost 6,000 were air force personnel, while 18,000 were ground troops and 4,700 were base area personnel.Major General George Wootten's 9th Division was the main element of this force, and consisted of two infantry brigades – the 20th and 24th; the division's third brigade – the 26th Brigade – had been detached for operations on Tarakan. The troops were supported by large number of American and Australian warships and air units. In preparation for the landing, a reconnaissance party including Sergeant Jack Wong Sue, was inserted into Kimanis Bay, British North Borneo, for close reconnaissance work using a Hoehn military folboat deployed from a Catalina aircraft.
Oboe 6 began on 10 June with simultaneous assaults by the 24th Brigade on the island of Labuan and the 20th Brigade on the coast of Brunei in the north-west of Borneo.As Japanese forces were holding positions away from the coast, these landings were unopposed. The 20th Brigade encountered little resistance. After the town of Brunei was secured on 13 June, the brigade continued its advance along the coast towards the south-west. Its objective was the Miri–Lutong area, with the 2/17th Battalion moving by land while the 2/13th Battalion made an amphibious landing at Lutong on 20 June. The Japanese forces withdrew as the Australians advanced, and there was little fighting during these operations. Patrols into the interior made by the 20th Brigade with the assistance of local Dayaks into the interior were involved in several sharp engagements.
While the 24th Brigade rapidly captured Labuan's airfield and town, it encountered sustained resistance from the Japanese garrison which was located in a well-defended stronghold.After heavy casualties were sustained during the 2/28th Battalion's initial attack against this position on 16 June it was decided to subject the area to a sustained bombardment. The battalion attacked again on 21 June with the support of tanks and rapidly defeated the Japanese forces. The fighting on Labuan cost the 24th Brigade 34 killed and 93 wounded. The Australian soldiers counted 389 Japanese dead and took 11 prisoners.
A week after the initial landing on Labuan, the Australians followed up with attacks on Japanese positions around Weston on the north-eastern part of Brunei Bay. 23 kilometres (14 mi) north-west of Brunei Bay, and then on to Jesselton. The heaviest fighting of the operations on the mainland took place on 27/28 June during the Battle of Beaufort, during which more than 100 Japanese defenders were killed. After this engagement the 24th Brigade undertook limited further advances in order to push the Japanese forces into the hills; the brigade's limit of exploitation was the Beaufort–Tenom railway and during this period the Australian commanders adopted a cautious approach to limit casualties. Nevertheless, clashes continued into August; on 3 August, the Japanese attempted to counterattack a position held by the 2/28th Battalion. At least 11 Japanese were killed in the fighting, for the loss of one Australian.The Australians then pushed inland along the single track railway that ran from Weston towards the junction at Beaufort,
The operations in North Borneo also involved a substantial civil affairs effort to assist the liberated civilian population; this was the largest such task undertaken by Australian forces during World War II. The 9th Division was heavily involved in providing aid to civilians and rebuilding houses and infrastructure which had been destroyed by the pre-invasion bombardments and subsequent fighting.
The conventional operations on British North Borneo were accompanied by a guerilla warfare campaign organised by Special Operations Australia (SOA). This involved two operations; Operation Agas in British North Borneo and Operation Semut in Sarawak.These operations succeeded the unsuccessful Operation Python which had been undertaken between October 1943 and January 1944.
Five SOA parties were inserted in North Borneo between March and July 1945. The Agas 1 and 2 parties established networks of agents and guerrillas in north-western Borneo. The Agas 4 and 5 parties were landed on the east coast of Borneo, and achieved little. The Agas 3 party investigated the Ranau area on the request of I Corps. The results of Operation Agas were mixed; its parties established control over their areas of operation, provided intelligence of variable quality and killed less than 100 Japanese.
As part of Operation Semut over 100 Allied personnel organised into four parties were inserted by air into Sarawak from March 1945. Most of these personnel were Australian. The Semut parties were tasked with collecting intelligence and establishing guerilla forces. The inhabitants of Sarawak's interior, who were known as Dayaks, enthusiastically joined the guerilla groups and SOA personnel led small private armies.No. 200 Flight RAAF and the Royal Australian Navy's Snake-class junks played important roles in this campaign by inserting SOA personnel and supplies.
The guerilla forces launched attacks to gain control of the interior of Sarawak while the 9th Division focused on the coastal area, the oilfields, plantations and the ports in North Borneo.The guerillas operated from patrol bases around Balai, Ridan and Marudi, as well as in the mountains, along several key waterways including the Pandaruan and Limbang Rivers, and along the railway that ran between Beaufort and Tenom. They sought to disrupt the Japanese troops' freedom of movement and interdicted forces as they withdrew from the main combat zone. The RAAF flew air strikes to support the lightly armed guerillas, who at times had to evade better-armed Japanese units. The campaign was highly successful, and it is estimated that over 1,800 Japanese were killed in north Borneo through guerilla actions.
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.The landing was preceded by a heavy aerial bombardment over the course of 20 days, while minesweepers worked to clear the area for 15 days, establishing safe lanes for the invasion fleet to pass and clearing proposed anchorages. These operations were undertaken inside the range of Japanese coastal guns; to protect the minesweepers, naval gunfire and aerial bombardment was used to suppress and neutralise the Japanese guns. Due to the unavailability of the Tarakan airfield, air support for the operation was provided by RAAF and US units based in the southern Philippines. Three minesweepers were lost during the clearance operations.
The invasion fleet sailed from Morotai Island on 26 June, arriving off Balikpapan on 29 June. The landing area was then subjected to over 45,000 rounds of preparatory fire from the Australian, US and Dutch warships supporting the landing.A deception plan was enacted to draw Japanese attention towards Manggar, with the Australians undertaking pre-landing operations and spreading disinformation. US underwater demolition teams cleared obstacles along the landing beach, as well as off Manggar, as part of the deception plan. For the landing operation, a total of 33,000 personnel were assigned, 21,000 of which were from the Australian 7th Division, under the command of Major General Edward Milford. This formation consisted of three brigades – the 18th, 21st and 25th – fighting together as a formation for the first time during the war. Three beaches were chosen for the landing on the southern coast between Klandasan in the east and Stalkoedo in the west; the initial assault was undertaken by three infantry battalions: the 2/10th on the extreme left, the 2/12th in the centre and the 2/27th Battalion on the right. The troops were landed at the wrong location as smoke from the pre-landing bombardment made navigation difficult, but the landing was unopposed and a beachhead was quickly established as follow on forces arrived.
Operating on the left, the 18th Brigade fought to capture several high features around Klandasan and to gain control of the town and secure the harbour and port facilities in Balikpapan north-west of the landing beaches, while the 21st Brigade landed on the right, tasked with advancing east towards several Japanese airfields at Sepinggang and Manggar, along the main coastal road. The 25th Brigade was held in reserve, but after landing on 2 July, pushed inland towards Batuchampar, 10 miles (16 km) from the initial landing site. Balikpapan town and the port were captured on 3 July, but mopping up continued into 4 July. Along the coast, the 21st Brigade crossed the Batakan Ketjil River, where it was held up on 3 July by strong Japanese resistance, which was overcome with naval gunfire support. The following day, after crossing the Manggar Besar, the brigade came up against even stronger Japanese opposition, supported by coastal artillery and mortars defending the airfield; despite landing tanks around the river, the Australians were held up for several more days until some of the guns were captured, and heavy air strikes overwhelmed the defenders.
Meanwhile, on 5 July, one of the 18th Brigade's infantry battalions – the 2/9th – along with the 2/1st Pioneer Battalion,was landed at Panadjam to clear the western shore of Japanese artillery, prior to the Allies opening the port. Against only limited opposition, the area around Panadjam was cleared within two days. Meanwhile, the airfields were secured by 9 July, but Japanese resistance was strong, utilising delaying tactics including booby traps, mines, sniping and small-scale raids. Strong resistance was met around Batuchampar where a Japanese battalion had established a stronghold, while others fought resolutely in tunnels around Manggar. Australian engineers were heavily tasked, working to clear over 8,000 mines and booby traps, as well as destroying over 100 tunnels.
Once Manggar airfield was secured, the 21st Brigade continued their advance towards Sambodja. 3 miles (4.8 km) back on 9 July. Air strikes and artillery helped reduce this position, while infantry worked to surround the position; this was not fully achieved and by the evening of 21/22 July, the remaining defenders withdrew further inland. Opposition in these areas was largely overcome by the end of July, but mopping-up operations around Balikpapan continued until the end of the war in August as Japanese troops withdrew to the rough high ground further inland. Operations to secure Balikpapan cost the Australians 229 killed and 634 wounded, while Japanese losses were placed at 2,032 killed. A further 63 were captured.Moving inland along a north-east road dubbed the "Milford Highway" by the Australians, the 25th Brigade advanced to contact with the Japanese rearguard, which was reduced with artillery support and then outflanked, triggering a withdrawal to a secondary position
In the aftermath of the campaign, Australian personnel remained in Borneo until late 1945 to restore civilian administration, oversee reconstruction efforts, supervising the surrender of Japanese troops, and liberating former Allied prisoners of war held in camps around Borneo.It has been claimed that Australian forces near Beaufort encouraged local fighters to massacre surrendered Japanese troops after the war in revenge for the Sandakan Death Marches, with almost 6,000 Japanese being killed. The historian Ooi Keat Gin states though that no documentary evidence supports these claims.
The amphibious operations undertaken by Australian forces throughout the Borneo campaign were, according to the historian Eustace Keogh the "outstanding feature" of the campaign, and represented the largest such operations that the Australians undertook during the war. They required vast amounts of naval and air support, as well as complex planning and co-operation between air, land and naval forces from several nations. A significant amount of time and resources were invested prior to the operation to train the forces assigned.The historian Peter Dennis assesses that the operations were of "doubtful value strategically...[but]...they were skillfully conducted". Casualties during the campaign on the Allied side amounted to about 2,100, while the Japanese suffered about 4,700 casualties. A considerable number of civilians were killed or wounded; for instance, the pre-invasion bombardment of Tarakan resulted in least 100 civilian casualties.
Despite the success of the Allied landings, because of the strategic situation, 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. In assessing the necessity of the campaign, historians such as Max Hastings have said that attacking these forces, already cut off from Japan, was a waste of resources. According to Hastings, "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". 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 NEI, 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.
The 8th Division was an infantry division of the Australian Army, formed during World War II as part of the all-volunteer Second Australian Imperial Force. The 8th Division was raised from volunteers for overseas service from July 1940 onwards. Consisting of three infantry brigades, the intention had been to deploy the division to the Middle East to join the other Australian divisions, but as war with Japan loomed in 1941, the division was divided into four separate forces, which were deployed in different parts of the Asia-Pacific region. All of these formations were destroyed as fighting forces by the end of February 1942 during the fighting for Singapore, and in Rabaul, Ambon, and Timor. Most members of the division became prisoners of war, waiting until the war ended in late 1945 to be liberated. One in three died in captivity.
The 9th Division was a division of the Australian Army that served during World War II. It was the fourth division raised for the Second Australian Imperial Force. The distinctions of the division include it being:
The Battle of Tarakan was the first stage in the Borneo campaign of 1945. It began with an amphibious landing by Allied forces on 1 May, code-named Operation Oboe One; the Allied ground forces were drawn mainly from the Australian 26th Brigade, but included a small element of Netherlands East Indies personnel. The main objective of the landing was capture of the island's airfield. While the battle ended with success for the Allied forces over the Japanese defenders, this victory is generally regarded as having not justified its costs. The airfield was so heavily damaged that it ultimately could not be repaired in time to make it operational for other phases of the Allied campaign in Borneo.
The Battle of Balikpapan was the concluding stage of Operation Oboe, the campaign to liberate Japanese-held British and Dutch Borneo. The landings took place on 1 July 1945. The Australian 7th Division, composed of the 18th, 21st and 25th Infantry Brigades, with a small number of Netherlands East Indies KNIL troops, made an amphibious landing, codenamed Operation Oboe Two, a few miles north of Balikpapan. The Allied invasion fleet consisted of around 100 ships. The landing had been preceded by heavy bombing and shelling by Australian and US air and naval forces. The Allied force totalled 33,000 personnel and was commanded by Major General Edward Milford, while the Japanese force, commanded by Rear Admiral Michiaki Kamada, numbered between 8,400 and 10,000, of which between 3,100 and 3,900 were combatants. After the initial landing, the Allies secured the town and its port, and then advanced along the coast and into the hinterland, capturing the two Japanese airfields. Major combat operations concluded around 21 July, but were followed by mopping-up operations, which lasted until the end of the war in mid-August. Australian troops remained in the area until early 1946.
The Battle of North Borneo took place during the Second World War between Allied and Japanese forces. Part of the wider Borneo campaign of the Pacific War, it was fought between 10 June and 15 August 1945 in North Borneo. The battle involved a series of amphibious landings by Australian forces on various points on the mainland around Brunei Bay and upon islands situated around the bay. Japanese opposition to the landings was sporadic initially, although as the campaign progressed a number of considerable clashes occurred and both sides suffered relatively significant casualties. While Allied conventional operations focused largely around the coastal areas, guerilla forces consisting of Dayak tribesmen and small numbers of Allied personnel from the Services Reconnaissance Department fought an unconventional campaign in the interior. Ultimately, the Allies were successful in seizing control of the region, although to a large extent the strategic gains that possession of North Borneo provided the Allies with were ultimately negated by the sudden conclusion of the war in August 1945.
The Markham and Ramu Valley – Finisterre Range campaign, was a series of actions in the New Guinea campaign of World War II. The campaign began with an Allied offensive in the Ramu Valley, from 19 September 1943, and concluded when Allied troops entered Madang on 24 April 1944. During the campaign, Australian forces – supported by Australian and US aircraft – advanced through the Markham and Ramu Valleys during which there were minor clashes with Japanese forces, which withdrew towards their main defensive line in the Finisterre Range. The central geographical and strategic feature of the campaign was the imposing Shaggy Ridge, running north-south in the Finisterres; this was the scene of a climactic battle during which the Australians assaulted the Japanese positions in December 1943 and January 1944. Following the fighting around Shaggy Ridge, the Japanese withdrew towards the northern coast of New Guinea, where they were pursued by Australian and US forces advancing through the Finisterres and along the coast from Saidor. Following the capture of Madang, the Japanese eventually withdrew to Wewak where further fighting took place in 1944 and 1945.
The Huon Peninsula campaign was a series of battles fought in north-eastern Papua New Guinea in 1943–1944 during the Second World War. The campaign formed the initial part of an offensive that the Allies launched in the Pacific in late 1943 and resulted in the Japanese being pushed north from Lae to Sio on the northern coast of New Guinea over the course of a four-month period. For the Australians, a significant advantage was gained through the technological edge that Allied industry had achieved over the Japanese by this phase of the war, while the Japanese were hampered by a lack of supplies and reinforcements due to Allied interdiction efforts at sea and in the air.
The Salamaua–Lae campaign was a series of actions in the New Guinea campaign of World War II. Australian and United States forces sought to capture two major Japanese bases, one in the town of Lae, and another one at Salamaua. The campaign to take the Salamaua and Lae area began after the successful defence of Wau in late January, which was followed up by an Australian advance towards Mubo as the Japanese troops that had attacked Wau withdrew to positions around Mubo. A series of actions followed over the course of several months as the Australian 3rd Division advanced north-east towards Salamaua. After an amphibious landing at Nassau Bay, the Australians were reinforced by a US regimental combat team, which subsequently advanced north up the coast.
The Battle of Labuan was an engagement fought between Allied and Imperial Japanese forces on the island of Labuan off Borneo during June 1945. It formed part of the Australian invasion of North Borneo, and was initiated by the Allied forces as part of a plan to capture the Brunei Bay area and develop it into a base to support future offensives.
The 18th Brigade was an infantry brigade of the Australian Army. The brigade briefly existed as a Militia formation prior to the First World War, but this was short lived. During the Second World War, the brigade was raised on 13 October 1939 and was one of the first three infantry brigades of the Second Australian Imperial Force to be formed. Initially commanded by Brigadier Leslie Morshead, it served in the United Kingdom in 1940–1941, where it helped bolster the British garrison in anticipation of a possible German invasion following the Fall of France. In early 1941, the brigade was transferred to the Middle East where it later took part in fighting against the Italians in Libya and then helped to defend the besieged port of Tobruk before fighting against the Vichy French in the Syria–Lebanon campaign. The 18th Brigade was withdrawn to Australia in early 1942, and it later took part in the fighting against the Japanese in Pacific fighting several campaigns in New Guinea between late 1942 and early 1944. Its final involvement of the war came in mid-1945 when it took part in re-taking Balikpapan. Following the end of hostilities, the 18th Brigade was disbanded on 3 January 1946.
The 2/16th Battalion was an infantry battalion of the Australian Army, serving during World War II. Attached to the 21st Brigade that was assigned to the 7th Division, the 2/16th was raised in 1940 as part of the Second Australian Imperial Force from volunteers drawn mainly from the state of Western Australia. After training in Australia, the battalion was deployed to the Middle East where it undertook defensive duties along the Egyptian–Libyan border in early 1941 before taking part in the Syria–Lebanon campaign, fighting against Vichy French forces in June and July. At the conclusion of the campaign, the 2/16th remained in Lebanon, contributing to the Allied occupation force there, before returning to Australia in early 1942 following Japan's entry into the war. In August 1942, they were committed to the fighting along the Kokoda Track and then later fought around Buna and Gona. After a period of rest and reorganisation in Australia, the battalion fought around Lae and then took part in the Finisterre Range campaign in 1943–44. Its final campaign of the war came in Borneo in July 1945. At the end of the war, the 2/16th were disbanded in January 1946.
The 2/48th Battalion was an infantry battalion of the Australian Army which served during the Second World War. Raised in Adelaide in South Australia in August 1940, the battalion formed part of the 26th Brigade and was initially assigned to the 7th Division, although it was later transferred to the 9th Division in 1941 when it was deployed to the Middle East. While there, it saw action during the siege of Tobruk and the First and Second Battles of El Alamein before being returned to Australia to take part in the fighting in New Guinea following Japan's entry into the war.
The 25th Brigade was a brigade-sized infantry unit of the Australian Army that served during the Second World War. Raised in July 1940 and consisting of three infantry battalions, the 25th Brigade initially served in the United Kingdom, where it formed part of the garrison tasked with defending against a possible German invasion. In 1941, the brigade was redeployed to the Middle East where it took part in the Syria–Lebanon campaign fighting several actions around Merdjayoun and Jezzine.
The 24th Brigade was a brigade-sized infantry unit of the Australian Army. Formed on 1 July 1940 as part of the Second Australian Imperial Force, the unit was raised for service during World War II. Originally formed as part of the 8th Australian Division the brigade was subsequently transferred to the newly created 9th Australian Division in December. The brigade served during the Western Desert Campaign, forming part of the Allied garrison during the Siege of Tobruk. Later, the brigade was withdrawn to Syria for occupation duties, but then later took part in the First and Second Battles of El Alamein. In early 1943, the brigade was returned to Australia to fight against the Japanese in the Pacific. In 1943–1944, the brigade fought in New Guinea, taking part in the landing at Lae and the Huon Peninsula campaign. Its final campaign came late in the war, when it took part in the Labuan landings and the Battle of North Borneo in mid-1945. After the war, the brigade was disbanded in early 1946.
The 2/27th Battalion was an infantry battalion of the Australian Army during World War II. Raised in May 1940 as part of the 7th Division from volunteers from the state of South Australia, the battalion was assigned to the 21st Brigade. After completing training in Australia, the 2/27th deployed to the Middle East in November 1940, and in early 1941 undertook defensive duties in the Western Desert. The battalion's first combat experience came against the Vichy French during the short Syria–Lebanon campaign during which it fought major engagements around Sidon and Damour. At the conclusion of the fighting in Syria, the battalion remained in the area as part of the Allied occupation force until early 1942 when it was returned to Australia to fight against the Japanese.
The Battle of Finschhafen was part of the Huon Peninsula campaign during World War II and was fought between Australian and Japanese forces. The fighting took place between 22 September and 24 October 1943 following the landing at Scarlet Beach, which was followed by a two-pronged advance on Finschhafen as the Australian 20th Infantry Brigade advanced on the town from the north, while the 22nd Infantry Battalion drove from the south, having advanced from the landing beaches east of Lae. After the capture of Finschhafen, the Japanese forces in the area withdrew towards Sattelberg where they sought to hold the Australians before launching a counteroffensive, which subsequently threatened the landing beach. This attack was repelled by American and Australian forces, with heavy casualties being inflicted on the Japanese. In the aftermath, the Australians went on the offensive, capturing Sattelberg, and then advancing towards the Wareo plateau.
The 2/24th Battalion was an infantry battalion of the Australian Army, which served during World War II. A unit of the all-volunteer Second Australian Imperial Force, it was formed in July 1940 from primarily Victorian volunteers and was known as "Wangaratta's Own" because of the time the battalion spent in the town during its formative period prior to deployment overseas. It served in North Africa in 1941–1942 as part of the 26th Brigade, which was assigned to the 7th Division, before being reassigned to the 9th Division. In early 1943, the battalion returned to Australia and later took part in campaigns against the Japanese in New Guinea in 1943–1944 and Borneo in 1945, before being disbanded in 1946. The 2/24th suffered the highest number of casualties of any 2nd AIF infantry battalion.
The Battle of Mount Tambu was a series of actions fought in the Salamaua area of the Territory of New Guinea between Allied and Japanese forces, which took place between 16 July and 18 August 1943, during World War II. The battle formed part of the wider Salamaua–Lae campaign and was fought in the final stages of the campaign, which had seen a combined Australian and US force advance from Wau towards Salamaua following the repulse of the Japanese attack on Wau in late January and early February 1943. After several frontal assaults on the position by Australian and US infantrymen were rebuffed by determined Japanese defenders, an indirect approach was sought and flanking moves were undertaken to cut off the Japanese supply route along the Komiatum Track. This succeeded in eventually forcing the Japanese off the position as they withdrew to avoid encirclement.
The Battle of Madang, fought between early February and late April 1944, was the break-out and pursuit phase of the Markham and Ramu Valley – Finisterre Range and Huon Peninsula campaigns, which were part of the wider New Guinea campaign of World War II. After overcoming the Japanese defences around Shaggy Ridge, the Australian forces descended the steep slopes of the Finisterre Range and pursued the withdrawing Japanese towards Bogadjim and then Madang on the north coast of New Guinea. There they linked up with US and Australian forces that had advanced along the coast from the Huon Peninsula, while the remnants of three Japanese divisions withdrew towards Wewak, where further fighting would take place throughout late 1944 and into 1945.
The Battle of Beaufort took place during the Second World War between Allied and Japanese forces. Part of the wider Borneo campaign of the Pacific War, it was fought between 26 and 28 June 1945 in North Borneo. The battle formed part of the Allied efforts to secure North Borneo in the final months of the war and saw two Australian infantry battalions attack the town, which was held by a force of around 800 – 1,000 Japanese. Over the course of several days heavy fighting took place before the Japanese began withdrawing on 29 June. While withdrawing, the Japanese were ambushed and suffered heavy casualties.
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