The 'Battle of Beaufort' was fought between Allied (primarily Australian) and Japanese forces as part of the 'Battle of North Borneo' within the context of the former’s recapture of the island of Borneo (26/28 June 1945).

The battle was part of the Allied efforts to secure North Borneo in the final months of the war, and involved two Australian infantry battalions in an attack on the town, which was held by between 800 and 1,000 Japanese. There was heavy fighting before the Japanese began to pull back on 29 June. While withdrawing, the Japanese were ambushed and suffered heavy casualties.

Beaufort was a town in British North Borneo, and is located on the northern bank of the Padas river in a location dominated on three sides by jungle-covered hills. The Padas river’s banks are swampy. The town was an important transport nexus as it stood at the junction of two railways, including a light railway which connected Weston with Jesselton, and a major river. Under the Japanese occupation of British Borneo, Beaufort was thus an important communications centre for the region’s Japanese forces.

Allied operations to retake Borneo from the Japanese began on 1 May 1945 with the 'Oboe I' amphibious landing on Tarakan off the island’s north-eastern coast. This was followed by 'Oboe VI' from 10 June to secure North Borneo. This undertaking had two phases: in the first, Brigadier S. H. W. C. Porter’s Australian 24^th Brigade Group was to secure the island of Labuan and Brigadier W. J. V. Windeyer’s Australian 20^th Brigade Group was to capture the town of Brunei; and in the second, which was to take place after the first had been completed, the region between Brunei Bay and Beaufort on the North Borneo mainland was to be occupied, as was the area of Miri, Lutong and Seria area of Sarawak. The Allied forces were then to construct bases in these regions, protect oil and rubber resources, and re-establish the civil administration.

At this time, there were several Japanese units of Lieutenant General Masao Baba’s 37^th Army in the Beaufort area. These included the 368^th Independent Battalion, which was part of Major General Taijiro Akashi’s 56^th Independent Mixed Brigade, as well as this same brigade’s engineer and signals units. Other units at Beaufort included the 1/25^th Independent Mixed Regiment, the 20^th Independent Machine Gun Battalion, part of the 103^rd Field Road Unit, the 11^th Southern Army Hospital and the 3^rd Company of the 10^th Sea Transport Battalion. The 368^th Independent Battalion had just completed a difficult march across the interior of Borneo, in the course of which it had suffered heavy losses.

After the landings on Labuan island and around Brunei earlier in the month, on 16 June the Australians crossed Brunei Bay and landed a force on the North Borneo mainland around Weston, coming ashore unopposed. This force consisted of two infantry battalions and supporting elements of the Australian 24^th Brigade group, detached from Major General G. F. Wootten’s Australian 9^th Division.

The purpose of the landing was to clear the area around Brunei Bay in order that it could be used as an advanced naval base for future operations. The 2/32^nd Battalion captured the town of Weston against light opposition. In the absence of roads leading inland, however, the battalion advanced along the single-track railway toward Beaufort, while the 2/43^rd Battalion landed unopposed around Mempakul, under cover of artillery firing from Labuan island, to secure the Klias peninsula together with the 2/11^th Commando Squadron, before moving by barge along the Klias river in concert with several motor gunboats. Reaching Kibidang on 23 June, the 2/43^rd Battalion then marched overland to the Padas river, linking with the 2/32^nd Battalion at Kandu. The capture of Beaufort, sitting at the junction of two railway lines, would provide the Australians with control of the railway that ran toward Jesselton. Beaufort lay on egress routes from the coast, and following the Australian landing on the mainland the Japanese sought to hold Beaufort from the Australians to allow their forces to withdraw.

The Japanese held Beaufort, and had forward positions covering avenues of approach up the Padas river and along the railway. In order to support their attack, the Australians brought forward 14 25-pdr field gun/howitzers. On 26 June, the two Australian battalions began their approach to the town. The 2/43^rd Battalion was assigned the task of the main assault, while the 2/32^nd Battalion was tasked with flank protection. Despite being slowed by torrential rain and difficult terrain, the 2/32^nd Battalion secured the Padas river’s southern bank, while one company of the 2/43^rd Battalion was sent to take the town and another marched to the flanks in order to find and occupy ambush positions along the route that the Japanese were expected to make their withdrawal. Meanwhile, two companies of the 24^th Brigade Group’s third battalion, the 2/28^th Battalion, which had been transferred from Labuan island, secured the lines of communication to the north of the river. The battalion was also tasked with the defence of the supporting artillery. The 2/43^rd Battalion’s attack began at 14.00 on 27 June, and the supporting artillery held its fire until the attack had begun so that the defenders would not be warmed of the impending attack.

The Japanese resistance was not co-ordinated effectively, and as a result the Australians had secured their objectives by the fall of night on the evening of 27/28 June. Throughout the night, however, the Japanese launched six counterattacks. These were eventually repulsed, although in places they had reached the stage of hand-to-hand combat. During these actions, one Australian company became isolated and on the morning of 28 June another was sent to its aid by attacking the Japanese force from the rear. Fighting its way through numerous Japanese positions throughout the afternoon, the company reached its objective early in the evening and launched its assault. The Australians landed a troop of tanks from the river, and engineers worked to clear a route forward for these vehicles, but the fighting had ended before the way had been cleared. Meanwhile, heavy artillery and mortar fire fell on the Japanese, who began to withdraw throughout the evening of 28 June. In doing so, at least 81 of them were killed in the ambush set by the Australians.

By 29 June, the Australians had captured the town, and mopping-up operations continued throughout the day. Meanwhile, a platoon of the 2/28^th Battalion patrolled to Lumadan, where they came under fire from the hills to the east. Artillery fire was called down and another platoon was despatched to assist. In the days immediately following the fighting, the Australians maintained pressure on the Japanese, and pushed them farther to the east with a series of patrol actions. With the capture of Beaufort, the Australians were able to open the railway linking Weston and Beaufort: improvised rolling stock (carriages pulled by Jeeps) was pressed into service to bring supplies forward. The Jeeps were supplemented early in July by a steam locomotive, and the railway was used to carry follow-on elements of the 2/28^th Battalion to Lumadan. This was followed from 6 July by farther advances to secure Papar using barges and the railway line between Beaufort and Membakut. The 2/32^nd Battalion entered the town on 12 July and began to use it as a patrol base.

The Australian casualties during the fighting around Beaufort amounted to seven men killed and 38 wounded, while at least 93 Japanese were killed and two taken prisoner.

The fighting around Beaufort was the only occasion in which the Japanese tried to resist the Australian advance in North Borneo. It was also last significant action fought in North Borneo, although minor engagements continued in the following months. The withdrawing Japanese were harried by artillery and air attacks as the Australians drove forward another 4.3 miles (7 km). Patrol clashes indicated that there would probably be an increase in Japanese resistance beyond Tenom. The 24^th Brigade Group undertook containment operations to the east of Beaufort, pushing along the railway track only as far as Tenom, and this secured Beaufort. The Australian commanders took great care to minimise casualties: for example, the 2/28^th Battalion used deception and harassing fire to secure an important knoll without suffering any casualties, and then held the position until 3 August when the Japanese launched a counterattack that was defeated with one Australian and 11 Japanese killed.

Elsewhere in North Borneo, the 20^th Brigade Group consolidated its gains around Brunei town at the southern end of Brunei Bay and began to exploit the area to the south-west, advancing toward Kuching, Miri, Lutong and Seria until the fighting in North Borneo came to an end in the middle of August.