The '2^nd Battle of Tarakan' was the battle between Australian and Japanese forces for the oil-rich island of Tarakan off the eastern coast of Borneo (1 May/21 June 1945).

This was the first stage in the Borneo campaign of 1945, and began with the 'Oboe I' amphibious assault on 1 May by Brigadier D. A. Whitehead’s Australian 26^th Brigade, but included a small element of Netherlands East Indies personnel. The main objective of the landing was the capture of the island’s airfield. While the battle ended with victory for the Allied forces over the Japanese, this success 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.

Tarakan is an island of triangular shape, apex to the south, some 2.5 miles (4 km) off the coast of Borneo. The island is about 15 miles (24 km) long from its northernmost point to the southern tip and 11 miles (18 km) wide toward the north of the island. The small island of Sadau is located about 0.5 mile (0.8 km) off Tarakan’s western coast. Almost all of Tarakan’s coast is swampy, and in 1945 mangroves on the northern half of the island stretched between 1 and 2 miles (1.6 and 3.2 km) inland, but the coastal mangroves in the southern part of the island were narrower. Inland from the swamps, most of central Tarakan comprised a series of steep and densely forested hills just over 100 ft (30 m) high. Tarakan is located 3° north of the equator and is characterised by a tropical climate. The maximum temperature for most days is about 27° C (80° F), and relative humidity is consistently high at about 90%.

In 1945, the town of Tarakan was the main settlement of the island, The town was located 2,000 yards (1830 m) inland, and was separated from the south-western coast by several small hills covered with low vegetation. Four piers used to dock oil tankers were located on this coast at the settlement of Lingkas, and were connected with the town of Tarakan by three surfaced roads. Tarakan airfield was located about 1 mile (1.6 km) to the north-west of Tarakan town. Of the island’s two oilfields, Sesanip oilfield was located at the north-eastern edge of the airfield while the larger Djoeata or Juata oilfield was 3 miles (4.8 km) to the north. The village of Djoeata was located on Tarakan’s north-western coast and linked to Djoeata oilfield by a track.

Before World War II, Tarakan formed part of the Netherlands East Indies and was an important centre of oil production: the two oilfields produced 80,000 barrels of oil per month in 1941. The seizure and exploitation of Tarakan’s oilfields was one of Japan’s early objectives during the Pacific War, and Japanese forces landed on the island’s eastern coast on 11 January. In the resulting '1^st Battle of Tarakan', the Japanese defeated the small Dutch garrison in two days of fighting in which half the defenders were killed. While the oilfields had been successfully sabotaged by the Dutch before their surrender, Japanese engineers were able to complete their swift restoration to production, and 350,000 barrels per month were extracted by a time early in 1944.

Following the Dutch surrender, Tarakan’s 5,000 inhabitants suffered under Japan’s occupation policies. The large number of troops stationed on the island caused food shortages, and many civilians consequently suffered from malnutrition. The Japanese also brought 600 Javanese labourers to Tarakan, and additionally forced an estimated 300 Javanese women to work as 'comfort women' on Tarakan after enticing them to travel with false offers of clerical and clothes-making jobs.

Tarakan’s value to the Japanese evaporated with the rapid advance of Allied forces into the area during 1944. The last Japanese oil tanker departed Tarakan in July 1944, and heavy Allied air raids later in the year destroyed the island’s oil production and storage facilities. Hundreds of Indonesian civilians may have also been killed by these raids. Allied aircraft also laid mines near Tarakan and, in combination with air and sea patrols, their presence prevented Japanese merchant vessels and transports from docking at the island.

In line with the island’s declining importance, the Japanese garrison on Tarakan was reduced early in 1945, and the 454^th Independent Battalion, one of the two infantry battalions based on the island, was withdrawn to Balikpapan, where it was destroyed by Major General E. J. Milford’s Australian 7^th Division during July in the 'Battle of Balikpapan', otherwise 'Oboe II'

The primary objective of 'Oboe I' was to secure and develop the island’s airfield so that it could be used to provide air cover for subsequent landings in Brunei, Labuan and Balikpapan, while the secondary objective was to secure Tarakan’s oilfields and bring them into operation as a source of fuel for the Allied forces in the theatre. The 3^rd Company of the Dutch Technical Battalion was responsible for this.

The headquarters of Major General G. F. Wootten’s Australian 9^th Division and of the 26^th Brigade were responsible for planning 'Oboe I'. This work began in early March when both units had arrived at Morotai island in the Netherlands East Indies in the area of Halmahera, and the final plan was completed on 24 April. The planners' work was hampered by poor working conditions and difficulties in communicating with General Douglas MacArthur’s Allied General Headquarters on Leyte in the Philippine islands group. As part of the planning process, each of Tarakan’s hills was assigned a code name: during the Australian campaigns in New Guinea, geographic features had been named on an ad hoc basis, and it was hoped that the selection of names before the start of the battle would improve the precision of subsequent planning and communications.

Allied planning was posited on the belief that Tarakan would be secured quickly, and it was expected that the operation would involve a short fight for the airfield followed by a 'consolidation' phase during which the island’s airfield and port would be developed to support subsequent Allied operations. The planners did not foresee significant fighting in Tarakan’s interior, and no plans were developed for operations in areas other than the landing beaches, the town of Tarakan and the airfield. The planners did, however, correctly anticipate that the Japanese would make their main stand in an area other than the invasion beach and would not be capable of mounting a large counterattack.

The Allied planning also expected that Tarakan could and would be transformed into a major base within days of the landing: it was intended that a wing of fighter aircraft would be based at Tarakan a mere six days after the landing, and that this force would be expanded to include a wing of attack aircraft nine days later and staging facilities for another four squadrons of aircraft within 21 days of the landing. It was also expected that the Australian 26^th Brigade Group and its supporting beach group would be ready to leave Tarakan by 21 May and that the Royal Australian Air Force units could be redeployed in the middle of June after providing support for the 'Oboe II' landing at Balikpapan.

The Allied planners possessed detailed intelligence on Tarakan and its defences. This intelligence had been gathered from a variety of sources which included signals intelligence, photographic reconnaissance flights and Dutch colonial officials. Tarakan was the Australian Services Reconnaissance Department’s first priority from November 1944. Before the invasion, Lieutenant General Sir Leslie Morshead’s Australian I Corps requested that the department provide intelligence on Japanese positions in northern and central Tarakan. A five-man party was landed on the island during the night of 25/26 April and successfully reconnoitred the defences on Tarakan’s north coast, though the operative who was assigned to the centre of the island became lost and did not reach this area. The operatives were withdrawn on the night of 29/30 April and landed on the mainland of Borneo. They were unable to transmit the intelligence they had collected, however, as their radio set malfunctioned. Members of the party eventually landed within the Allied beach-head on Tarakan on 3 May to report to the 26^th Brigade Group, but Whitehead was disappointed with the results of this operation and made no further use of the Services Reconnaissance Department during the battle.

The Allied force responsible for the recapture of Tarakan was based on the highly experienced Australian 26^th Brigade Group of nearly 12,000 men. This brigade had been formed in 1940 and seen action in North Africa and New Guinea. The brigade’s infantry component comprised the 2/23^rd, 2/24^th and 2/48^th Battalions, which were all combat-experienced, and these were joined by the 2/4^th Commando Squadron and the 2/3^rd Pioneer Battalion, which fought as infantry in this battle. The brigade group also included the 2/7^th Field Regiment equipped with 24 25-pdr gun/howitzers, one squadron of the 2/9^th Armoured Regiment operating 18 Matilda II infantry tanks, one company of the 2/2^nd Machine Gun Battalion, the 53^rd Composite Anti-Aircraft Regiment and two engineer field squadrons. These combat units were supported by a large number of logistics and medical units, including the 2^nd Beach Group, whose role was to land supplies from the invasion fleet. While the 26^th Brigade Group greatly outnumbered the known strength of Tarakan’s defenders, the Allies committed this large force as their previous experience indicated that it would be difficult to defeat the Japanese force should the latter retreat into the island’s rugged interior.

The 26^th Brigade Group was supported by Allied air and naval units. The air units were drawn from Air Commodore F. R. M. Scherger’s Australian 1^st Tactical Air Force and Major General Paul B. Wurthsmith’s US 13^th Army Air Force, and included both fighter and bomber squadrons. The naval force was drawn from Vice Admiral Thomas C. Kinkaid’s US 7^th Fleet and included several Royal Australian Navy warships and transports. Since the main objective of attacking Tarakan was to use the island’s airstrip, the invasion force also included a large number of RAAF ground units, including No. 61 Airfield Construction Wing with Nos 1 and 8 Airfield Construction Squadrons.

The force which landed on Tarakan included nearly 1,000 US and Free Dutch troops. The US troops included the US Army engineers who manned the invasion force’s LCM and LCVP landing craft, and Company A of the US Army’s 727^th Amphibian Tractor Battalion, which operated the LVT craft, and US Navy 'Seabee' construction detachments aboard the LSTs. The Free Dutch forces were organised into a company of Ambonese infantry commanded by Dutch officers, and a civil affairs unit.

At the time of the Allied landing, the Japanese force on Tarakan numbered 2,200 men drawn from the Imperial Japanese army and Imperial Japanese navy. The largest unit was the 740-man 455^th Independent Battalion commanded by Major Tadao Tokoi. There were also 150 army support troops on Tarakan. The navy’s contribution to Tarakan’s garrison comprised 980 seamen under the command of Commander Kaoru Kaharu. The main naval unit was the 600-man 2^nd Naval Garrison Force, which was trained to fight as infantry and operated several coastal defence guns. The 350 Japanese civilian oil workers on Tarakan were also expected to fight in the event of an Allied attack. The Japanese force included about 50 Indonesians serving in a home guard unit. Tokoi directed the overall defence of Tarakan, though relations between the army and navy were poor.

The Japanese forces were concentrated around Lingkas, Tarakan’s main port and the site of the only beaches well suited for amphibious operations. The defenders had spent the months before the invasion constructing defensive positions and laying mines. These fixed defences were used extensively during the battle, in which the Japanese tactics were concentrated on the tenacious defence of pre-prepared positions. The Japanese undertook no large counterattacks, and most offensive actions were limited to those of small parties of raiders which attempted to infiltrate the Australian lines.

The Japanese force on Tarakan was warned of the impending invasion in April, before the Allies began their pre-invasion bombardment of the island. The island’s commander received a radio signal warning him of imminent attack, and the commander of Tarakan’s oil depot was ordered to destroy the oil wells on 15 April. It is possible that this warning may have been issued as a result of a security leak either from the Chinese nationalist army’s representative to Australia or from MacArthur’s headquarters. This warning exercised no effect on the subsequent battle, however, as the Japanese had been preparing defences to resist invasion for several months and the Japanese were aware of the large Allied force which was being assembled at Morotai island to attack Borneo.

Before the arrival of the invasion force, the Japanese garrison on Tarakan and Borneo was subjected to intense air and naval attacks from 12 to 29 April. The RAAF and USAAF also mounted air attacks against Japanese bases in Japanese-occupied China, French Indo-China and the Netherlands East Indies in order to suppress Japanese air units throughout the region. These attacks destroyed all Japanese aircraft in the Tarakan area. The bombing of Tarakan increased in intensity five days before the landing, was focused on the areas adjoining the planned landing beaches at Lingkas, and sought to neutralise the Japanese defences in these areas. The oil storage tanks at Lingkas were key targets as it was feared that the oil in these tanks could be released and ignited and used against Allied troops. These bombardments forced much of Tarakan’s civilian population to flee inland, and at least 100 civilians were killed or wounded.[1]

The Tarakan attack force was assembled at Morotai during March and April 1945. The 26^th Brigade Group was transported from Australia to Morotai by US Army transport vessels, arrived during the middle of April and began to prepare their equipment for an amphibious landing. As a result of a shortage of shipping, all units were ordered to leave non-essential vehicles at Morotai when they began to embark in their assault transports on 20 April. Scherger sought to resist this order, but was overridden by his superior officer, Air Vice Marshal W. D. Bostock, head of the RAAF Command. Most units had been embarked by 22 April and the assault troops practised landing operations for several days. A small convoy of ships carrying a force ordered to capture Sadau island, off the western coast of Tarakan, departed Morotai on 26 April, and the main invasion convoy of 150 ships sailed on the following day.

As a result of the need to clear both the large number of naval mines round Tarakan and the extensive beach obstacles at Lingkas, the Allies did not attempt a surprise landing. A group of US minesweepers and destroyers arrived off Tarakan on 27 April and began clearing mines, of which most had been laid by Allied aircraft. This operation had been completed by 1 May at a cost of two small minesweepers damaged. US PT-boats also arrived off Tarakan on 28 April and illuminated and strafed the invasion beaches at night to prevent the Japanese from repairing their beach defences. The PT-boats also attacked seven small Japanese freighters and luggers anchored at Lingkas, sinking or damaging all but one of them.

On 30 April, the 2/4^th Commando Squadron and the 57^th Battery of the 2/7^th Field Regiment were landed on the nearby Sadau island with orders to support the engineers tasked with clearing the obstacles off the invasion beaches. This force rapidly secured the undefended island, and this was the first occasion that Australian soldiers had landed on non-Australian territory in the Pacific since a time late in 1941. The only Allied losses in this operation were aboard the US destroyer Jenkins, which was damaged when she struck a mine while supporting the landing.

The task of clearing the beach obstacles at Lingkas was assigned to the 2/13^th Field Company. These defences comprised rows of barbed wire, wooden posts and steel rails which extended 125 yards (115 m) from the beach. At 11.00 on 30 April, eight parties of engineers went forward in LVTs and landing craft to clear the obstacles. The engineers were supported by the artillery sited on Sadau island, the guns of Allied warships, and aircraft. Operating under Japanese fire, the engineers cleared all the obstacles. Although heavy casualties had been expected, the 2/13^th Field Company completed its task without loss.

The main invasion force arrived off Tarakan in the early hours of 1 May. Supported by a heavy air and naval bombardments, the 2/23^rd Battalion and 2/48^th Battalion made an amphibious landing at about 08.00. The 2/23^rd Battalion disembarked from US LVTs into deep mud at Green Beach on the southern flank of the beach-head, and overcame several small Japanese positions in the hills around Lingkas. At the fall of night the battalion dug in along the main road to the town of Tarakan, which had been designated as the 'Glenelg Highway' by the Australian planners'. The 2/48^th Battalion had a much easier landing at Red Beach on the northern end of the beach-head, where most men disembarked from their LVTs near dry land. The battalion pushed north along the 'Anzac Highway' and nearby hills, and rapidly secured a number of pillboxes behind the beach as well as the oil storage tanks. By the end of the day the 2/48^th Battalion held positions in the hills to the west of Tarakan town. The 2/24^th Battalion also began landing on 'Red Beach' from 09.20, and spent most of the day in reserve. The unit received orders to advance to the north along the 'Anzac Highway' late in the afternoon, and met no opposition. By the fall of night the Australian beach-head extended for 2,800 yards (2560 m) along the shore and as much as 2,000 yards (1830 m) inland. However, Japanese snipers were active within this perimeter during the night of 1/2 May, and the 2/2^nd Pioneer Battalion, which was the main unit of the 2^nd Beach Group, fought several small actions with isolated Japanese forces. Allied casualties were lighter than expected: 11 men had been killed and 35 wounded. The light Japanese resistance was attributed to the heavy pre-landing bombardment forcing Tarakan’s defenders to abandon their formidable defences at Lingkas.

While the infantry was successful in securing a beach-head, the landing was hampered by the poor beach conditions. Many Australian vehicles became bogged in the Lingkas beach’s soft mud, and seven LSTs were stranded after their commanders misjudged their ships' beachings: these LSTs were not refloated until 13 May. The small area of solid ground within the beach-head led to severe congestion and resulted in none of the 2/7^th Field Regiment’s guns being brought into action until the afternoon of the landing. The congestion was made worse by much of the RAAF’s ground force being landed on 1 May with large numbers of vehicles.

After securing the beach-head, the 26^th Brigade Group advanced eastward into Tarakan town and northwarc in the direction of the airfield. The Australians met increasingly determined resistance as they moved inland. The task of capturing the airfield had been allocated to the 2/24^th Battalion, whose initial attack during the night of 2 May was delayed when the Japanese detonated large explosive charges, and the airstrip was not secured until 5 May. While the capture of the airfield achieved the 26^th Brigade Group’s primary task, the Japanese still held Tarakan’s rugged interior.

During the first week of the invasion, 7,000 Indonesian refugees passed into the advancing Australian lines. This was a larger number than had been expected, and the refugees, many of them in poor health, overwhelmed the Dutch civil affairs unit. Despite the devastation caused by the Allied bombardment and invasion, most of the civilians welcomed the Australians as liberators, and hundreds of Indonesian civilians later worked as labourers and porters for the Allied force.

General Sir Thomas Blamey, the commander of the Australian Military Forces, made an inspection tour of Tarakan on 8 May. During a meeting with Whitehead, Blamey directed that the 26^th Brigade Group should 'proceed in a deliberate manner' in clearing the rest of the island now that the main objectives of the invasion had been completed.

In order to secure the island and protect the airstrip from attack, the 26^th Brigade Group was forced to clear the Japanese from Tarakan’s heavily forested hills, where some 1,700 Japanese troops held positions in the island’s northern and central ares. These positions were protected by booby traps and mines. While attacks on these positions necessarily entailed costly infantry fighting, the Australian troops made heavy use of their available artillery and air support to minimise casualties. The Australian tanks could provide only limited support to the infantry as Tarakan’s thick jungle, swamps and steep hills often confined their movement to tracks and roads. As a result, tanks generally could not be used to spearhead attacks, and their role was limited to providing supporting fire for infantry assaults, with artillery the preferred source of direct support.

The 2/3^rd Pioneer Battalion and the Free Dutch company were assigned responsibility for securing the south-eastern portion of Tarakan. The pioneers began advancing to the east of Tarakan town on 7 May, but encountered unexpectedly strong Japanese resistance. From 10 May, the battalion was halted at the 'Helen' feature, which was defended by about 200 Japanese troops. During the fighting at 'Helen', Consolidated B-24 Liberator four-engined heavy bombers were used for close air support for the first time, and Lockheed P-38 Lightning twin-engined fighter-bombers dropped napalm immediately after the bombing. This combination proved particularly effective, and became the standard form of air support requested by the Australians. The Japanese force withdrew from 'Helen' on 14 May after suffering about 100 casualties, and the 2/3^rd Pioneer Battalion reached Tarakan’s eastern coast on 16 May. The battalion had lost 20 men killed and 46 wounded in this operation. During this period the Free Dutch company secured the remainder of southern Tarakan, and encountered little resistance during its advance.

The US and Australian navies continued to support the invasion once the landing had been completed. US PT-boats sank at least a dozen small craft off Tarakan and in rivers on the coast of Borneo between 1 and 10 May. These PT-boats carried Netherlands Indies Civil Administration interpreters on most patrols, and these men interrogated members of the local population to gather information on Japanese movements. The Japanese battery at Cape Djoeata on Tarakan’s northern coast was also knocked out by the US destroyer escort Douglas A. Munro on 23 May.

The Japanese garrison was gradually destroyed, with the survivors abandoning their remaining positions in the hills and withdrawing to the north of the island on 14 June. On this day 112 Chinese and Indonesian labourers left the Japanese-held area with a note from a senior Japanese officer asking that they be well treated. While Radio Tokyo announced that Tarakan had fallen on 15 June, the last organised Japanese resistance was encountered on 19 June and Whitehead did not declare the island secure until 21 June.

While the 26^th Brigade Group’s infantry fought the Japanese in the hills, the RAAF engineers of No. 61 Airfield Construction Wing were engaged in a major effort to bring Tarakan’s airfield back into operation. As the airfield had been heavily damaged by pre-invasion bombing and lay in marshy terrain, repair proved much more difficult than had been expected, and the task therefore took no less than eight weeks rather than the expected single week. Extensive use was made of Marston Mat, interlocking steel plates laid down like matting.

The airfield was finally opened on 28 June, but this was too late for it to play any role in supporting the 'Oboe VI' andings in Brunei or Labuan on 10 June, or the 'Oboe II' landings at Balikpapan. However, the RAAF’s No. 78 Wing was based on the airfield from 28 June and flew in support of the Balikpapan operation until the end of the war.

Efforts to restart production at Tarakan’s oilfields were delayed by the serious damage to the facilities and Japanese hold-outs, and the oilfields did not become operational until after the war.

After the end of organised resistance, the surviving Japanese on Tarakan split into small parties which headed to the north and east of the island. The 26^th Brigade Group’s main combat units were allocated sections of Tarakan, which they swept for Japanese. Many Japanese attempted to cross the strait separating Tarakan from the mainland of Borneo but were intercepted by Allied naval patrols. Allied troops also searched for Japanese on Bunyu island, 15 miles (24 km) to the north-east of Tarakan.

From the first week of July the surviving Japanese became increasingly short of food and attempted to return to their old positions in the centre of the island and to raid Australian positions in search of food. As their hunger increased more Japanese surrendered. Australian units continued to patrol in search of Japanese until the end of the war, with several Japanese being killed or surrendering each day. These operations cost the 26^th Brigade Group another 36 casualties between 21 June and 15 August. About 300 Japanese soldiers evaded the Allied patrols, and surrendered only at the end of the war in the middle of August.

The 26^th Brigade Group remained on Tarakan as an occupation force until 27 December 1945, although most of its units were disbanded in October. The brigade’s headquarters returned to Australia early in 1946 and was formally disbanded at Brisbane in January of that year.

Tarakan’s oilfields were repaired and brought back into production. Engineers and technicians had arrived shortly after the Allied landing and the first oil pump was restored on 27 June. By October the island’s oilfields were producing 8,000 barrels per day and providing employment for many Tarakanese civilians.

The '2^nd Battle of Tarakan' emphasised the importance of combined arms warfare, and especially the need for infantry to co-operate with and be supported by armour, artillery and engineers in jungle warfare.

The 26^th Brigade Group’s casualties were high in comparison with those of the other landings in the Borneo campaign. The brigade suffered more than twice the casualties that the Australian 9^th Division’s other two brigades suffered during their operations in North Borneo, and 23 more fatalities than the Australian 7^th Division incurred at Balikpapan. The 26^th Brigade Group’s higher losses may be attributable to the inability of Tarakan’s garrison to withdraw in the way that garrisons in North Borneo and Balikpapan did.

The landing force’s achievement was largely nullified by the fact that the island’s airfield could not be brought back into action swiftly. The faulty intelligence assessment, which led the RAAF planners to believe that the airfield could be repaired, represented a major failing. Moreover, the RAAF’s performance at Tarakan was often poor. This performance may have resulted from the low morale prevalent in many units and the 'Morotai Mutiny' disrupting the 1^st TAF’s leadership.

As with the rest of the Borneo campaign, the Australian operations on Tarakan remain controversial. Debate continues over whether the campaign was a meaningless 'sideshow', or whether it was justified in the context of the planned operations to both invade Japan and liberate the rest of the Netherlands East Indies, which were both scheduled to begin in 1946. The Australian official historian’s judgement that 'the results achieved did not justify the cost of the Tarakan operation' accords with the generally held view of the battle.