1945 engagement in Borneo
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.
Following several weeks of air attacks and a short naval bombardment, soldiers of the Australian 24th Brigade were landed on Labuan from American and Australian ships on 10 June. The Australians quickly captured the island's harbour and main airfield. The greatly outnumbered Japanese garrison was mainly concentrated in a fortified position in the interior of Labuan, and offered little resistance to the landing. The initial Australian attempts to penetrate the Japanese position in the days after the invasion were not successful, and the area was subjected to a heavy bombardment. A Japanese raiding force also attempted to attack Allied positions on 21 June, but was defeated. Later that day, Australian forces assaulted the Japanese position. In the following days, Australian patrols killed or captured the remaining Japanese troops on the island. A total of 389 Japanese personnel were killed on Labuan and 11 were captured. Australian casualties included 34 killed.
After securing the island, the Allied forces developed Labuan into a significant base. The 24th Brigade left from the island to capture the eastern shore of Brunei Bay in late June, and the island's airfield was repaired and expanded to host Royal Australian Air Force units. While occupying Labuan, the Allies had to reconstruct the island's infrastructure and provide assistance to thousands of civilians who had been rendered homeless by the pre-invasion bombardment. Following the war, a major Commonwealth War Graves Commission cemetery was established on Labuan.
Background.
Labuan is a small island in the mouth of Brunei Bay with an area of . Before the Pacific War, it formed part of the British-administered Straits Settlements and had a population of 8,960. The island had a town, Victoria, on its south coast which fronted onto Victoria Harbour, with a population of 8,500 and limited port facilities. Aside from a beach just to the east of Victoria, the coast was ringed by coral.
On 3 January 1942, Japanese forces captured Labuan unopposed during the Battle of Borneo. The Japanese developed two airfields (Labuan and Timbalai) on the island, which were built by labourers who had been conscripted from the Lawas and Terusan regions of mainland Borneo. The island population was also subjected to harsh occupation policies. After Japanese forces suppressed a revolt at the town of Jesselton in late 1943, which was led by Chinese-ethnic civilians, 131 of the rebels were held on Labuan. Only nine rebels survived to be liberated by Australian forces in 1944. Until mid-1944, few Japanese combat units were stationed in Borneo.
In March 1945 the Australian Army's I Corps, whose main combat elements were the veteran 7th and 9th Divisions, was assigned responsibility for liberating Borneo. Planning for the offensive was undertaken over the following weeks. While invading the Brunei Bay area did not form part of the initial iteration of the plans, it was added in early April after a proposed landing on Java was cancelled. The main purpose of attacking Brunei Bay was to secure it as a base for the British Pacific Fleet (BPF), and gain control of oil fields and rubber plantations in the area. Labuan was to be developed as an airbase and form part of a string of strategic positions which would allow the Allies to control the seas off the Japanese-occupied coast between Singapore and Shanghai.
While the liberation of the Brunei area had been authorised by the United States Joint Chiefs of Staff, it was not supported by the British Chiefs of Staff Committee. The British leadership did not want the BPF to be diverted from the main theatre of operations off Japan and preferred to establish a base for the fleet in the Philippines. In response to a suggestion from the Joint Chiefs of Staff that Brunei Bay could support future operations in south-east Asia, the Chiefs of Staff Committee judged that it would take too long to establish facilities there, especially as Singapore might have been recaptured by the time they were complete.
Preparations.
Allied planning.
The plans for the invasion of Borneo evolved considerably during April. Initially, the offensive was to commence on 23 April with the landing of a brigade from the 6th Division on the island of Tarakan, off the east coast of Borneo. The 9th Division would then assault Balikpapan followed by Banjarmasin in south-east Borneo. These positions would be used to support the invasion of Java by the remainder of I Corps. After the attack on Java was cancelled, it was decided to employ two brigades of the 7th Division at Brunei Bay, and I Corps conducted further preparations on this basis. However, on 17 April General Douglas MacArthur's General Headquarters (to which I Corps reported) swapped the roles of the 7th and 9th Divisions. Accordingly, the final plan for the attack against Borneo specified that one of the 9th Division's brigades would land on Tarakan island on 29 April (later postponed to 1 May), with the remainder of the division to invade the Brunei Bay area on 23 May. The 7th Division was scheduled to assault Balikpapan on 1 July. The Borneo campaign was designated the "Oboe" phase of the Allied offensive through the southern Philippines towards the Netherlands East Indies, and the landings at Tarakan, Brunei Bay and Balikpapan were designated Operations Oboe One, Six and Two respectively.
The 9th Division began to move from Australia to the island of Morotai in the Netherlands East Indies, where the Borneo campaign would be staged, in March 1945. The division had seen extensive combat in North Africa and New Guinea, and its officers and enlisted men were well trained for amphibious operations and jungle warfare. However, the 9th Division had been out of action since early 1944, leading to poor morale among its combat units. A large number of support, logistics and Royal Australian Air Force (RAAF) units were assigned to the division for the operations at Brunei Bay, taking its strength to over 29,000 personnel (including 1,097 in United States and British units).
Final preparations for the landings in the Brunei Bay area took place in May 1945. After shortages of shipping delayed I Corps' movement from Australia to Morotai, General Headquarters agreed on 8 May to reschedule the operation from 23 May to 10 June. The 9th Division's staff completed their plans for operations in the Brunei Bay area on 16 May. The 24th Brigade Group was assigned responsibility for capturing Labuan, and the 20th Brigade Group was tasked with securing Brunei and Muara Island. Both brigades were to land simultaneously on the morning of 10 June. The invasion of the Brunei Bay region was to be preceded by attacks on Japanese bases and transport infrastructure across western and northern Borneo by United States and Australian air units, as well as three days of minesweeping operations in the bay itself.
The 24th Brigade Group was commanded by Brigadier Selwyn Porter. His main combat units for operations on Labuan were the 2/28th and 2/43rd Battalions, the 2/11th Commando Squadron and the 2/12th Field Regiment. In addition, a squadron from the 2/9th Armoured Regiment (equipped with Matilda II tanks), a company of the 2/2nd Machine Gun Battalion and a range of engineer, signals and logistics units formed part of the brigade group. A party of 13 officers from the British Borneo Civil Affairs Unit (BBCAU) was also attached to the 24th Brigade and were tasked with restoring the colonial government on the island and distributing supplies to its civilian population. The 24th Brigade's third infantry battalion, the 2/32nd Battalion, was assigned to the 9th Division's reserve force. Porter and the 2/28th Battalion's commander, Lieutenant Colonel Hugh Norman, had a difficult relationship which generated ill-feeling between the two men and their respective headquarters. Porter considered relieving Norman of command before the landing on Labuan in the belief that he was exhausted and not capable of effectively leading his battalion, but decided against doing so after Norman made an emotional appeal to remain in his position.
The plans for the capture of Labuan specified that the 24th Brigade Group's two infantry battalions were to land simultaneously on the beach near Victoria (designated Brown Beach) at 9:15 am, with the 2/28th Battalion coming ashore on the western side of the beach and the 2/43rd to the east. The 2/11th Commando Squadron was to be initially held in reserve on board the invasion fleet. The brigade group's objectives were to secure a beachhead, capture the main airfield (located north of Victoria and designated "No. 1 Strip" by the Australians), destroy the Japanese garrison, and prepare for further operations on the eastern shore of Brunei Bay. Priority was given to rapidly opening the port and airfield so that they could be used to support other operations.
Porter expected that fighting for the main objectives would begin soon after the landing, and decided to begin landing his artillery and heavy mortars with the assault waves of infantrymen, just before the tanks came ashore. The 2/28th Battalion was initially assigned responsibility for securing Victoria and Flagstaff Hill to its north, while the 2/43rd Battalion was tasked with capturing the airfield. Once these areas were in Australian hands, the 2/28th Battalion would secure the western part of the island while the 2/11th Commando Squadron captured the western shore of Victoria Harbour. Due to the Australian Army's manpower shortages, all elements of the 9th Division were under orders to minimise their casualties during the Borneo Campaign and unit commanders would rely heavily upon the available air and artillery support during operations. The Australians estimated that the Japanese garrison on Labuan comprised 650 personnel, made up of 400 airfield troops, 100 naval troops and 150 other lines-of-communications personnel.
Japanese preparations.
As the Allies advanced towards Borneo, additional units were dispatched from Japan during the second half of 1944 and the 37th Army was established in September to coordinate the island's defence. In December 1944, Japanese staff officers deduced that it was likely that Australian troops would be landed at strategic points on the east and west coasts of Borneo in about March the next year (by which time they also expected United States forces to have liberated the Philippines). Accordingly, several Japanese units stationed in north-east Borneo were ordered to march to the western side of Borneo. This movement proceeded slowly, owing to the distances involved and disruptions caused by Allied air attacks.
By June 1945 around 550 Japanese military personnel were stationed on Labuan. The main unit on the island was the 371st Independent Infantry Battalion (almost in its entirety, save for one company located elsewhere) with a strength of around 350. This battalion formed part of the 56th Independent Mixed Brigade, which had arrived at Tawao in north-east Borneo from Japan in July 1944 with six infantry battalions. During early 1945 the brigade headquarters, 371st Independent Infantry Battalion and three other battalions marched across the island to assume responsibility for defending the Brunei Bay area. Many of the 56th Independent Mixed Brigade's soldiers fell sick during the march, and all four combat battalions were considerably below their authorised strength by the time they arrived at Brunei Bay. In June 1945 the 371st Independent Infantry Battalion was commanded by Captain Shichiro Okuyama. A detachment of about 50 men from the 111th Airfield Battalion was also on Labuan, along with around 150 men assigned to other small units. In line with Japanese doctrine, the Labuan garrison did not make preparations to contest the Allied landing force as it came ashore. Instead, it constructed defensive positions inland from the island's beaches. Documents captured by Australian soldiers during the fighting on Labuan indicated that Okuyama had instructions to attempt to withdraw his force from the island if the battle went against him.
Battle.
Pre-invasion operations.
Australian and United States air units began their pre-invasion attacks on north Borneo in late May. The first attack on the Brunei Bay area took place on 3 May, and included a raid targeting the town of Victoria on Labuan. A large number of further attacks were conducted to suppress Japanese airfields