The Battle of Tawau was a combined air and ground engagement fought between Indonesian and Commonwealth forces in the Tawau Division of Sabah, from 7 December 1963 to 10 February 1964, during the Indonesia–Malaysia Confrontation. The Indonesian objective was to capture Kalabakan as a strategic foothold, thereby facilitating a broader advance to seize the key towns of Tawau, Lahad Datu and Sandakan.
Geography The Tawau Division is located on the eastern flank of Sabah, bordering the Indonesian province of North Kalimantan along the Malaysia–Indonesia land boundary, which stretches approximately . Additionally, the maritime boundary in the Celebes Sea extends for a further , delineating territorial waters between the two nations.
The division includes the northern portion of Sebatik Island, which has been bisected between Malaysia and Indonesia since the 1915 Boundary Treaty Agreement, making it a critical point of bilateral interest and potential friction.
At the time of the Indonesia–Malaysia Confrontation, Tawau town had an estimated population of 15,000 residents, of whom roughly three-fifths were Indonesian immigrants. The surrounding region consists of tropical rainforests, swamps, coastal zones, and a network of rivers, contributing to its agricultural and commercial significance. During that period, the east coast of Sabah—including Tawau—emerged as one of the most economically advanced regions in the state, largely driven by the cultivation of rubber, cocoa, tea, oil palm, and hemp, as well as a thriving timber industry. The coastal towns of eastern Sabah served as key economic engines for the region.
Tawau's strategic value was first recognised during the Second World War, when Imperial Japanese forces developed it into a military base. Although the base was subsequently abandoned following Japan's surrender in 1945, rising tensions during the Indonesia–Malaysia Confrontation prompted its reactivation in July 1963.
A combined Malaysian and Commonwealth security force was established in response to the threat, with the East Sabah Brigade—under the command of Brigadier Jack Glennie—assigned responsibility for the defence of East Sabah.
To secure the Tawau Residency, multiple military units were deployed to the region, including elements of the 10th Gurkha Rifles, the 3rd Battalion, Royal Malay Regiment (3 RMR), the 1st Battalion, King's Own Yorkshire Light Infantry (1 KOYLI), and the 2nd Regiment, Federation Reconnaissance Corps (now the Royal Armoured Corps). These units operated alongside the Police Field Force and the Vigilante Corps (Malaysia's Home Guard). Platoons from these formations were strategically dispersed throughout the region to monitor key routes and respond rapidly to any incursions by Indonesian forces.
Background Following the formation of Malaysia in September 1963, the government of Indonesia initiated a campaign of political opposition and military hostility, which escalated into a broader conflict known as the Indonesia–Malaysia Confrontation. The confrontation in East Malaysia was preceded by a series of border incursions, reconnaissance activities, and harassment actions conducted along the Kalimantan–East Malaysia frontier, beginning with the Tebedu Incident in April 1963.
These preliminary operations were designed to destabilise the newly formed Malaysian Federation, undermine local governance, and test the defensive readiness of the Commonwealth and Malaysian security forces stationed in Sabah and Sarawak.
Indonesian Strategy Indonesian strategic intent in the Sabah theatre centred on the progressive seizure of key population and logistical centres, beginning with Kalabakan and culminating in the occupation of Tawau and onwards movement toward Sandakan. The campaign was conceived as a phased, land-based advance, supported by irregular warfare and psychological operations (PSYOPS) aimed at destabilising the local population, undermining civil authority, and facilitating insurgent collaboration.
Intelligence gathering and psychological operations
Commencing in early 1963, the Indonesian Armed Forces initiated covert reconnaissance operations within Sabah and Sarawak. Reconnaissance parties, composed of Indonesian special forces operatives in coordination with local communist sympathisers, were inserted to collect topographical, military, and civil intelligence.
According to official British reporting, several reconnaissance elements were apprehended during infiltration attempts as early as April 1963, highlighting pre-conflict intelligence preparations by Indonesian forces.
Forward deployment and irregular warfare support
By October 1963, elements of the 1st Battalion, Commando Operations Corps ( – KKO), operating as a precursor to the modern Indonesian Marine Corps, were forward-deployed from Surabaya to positions on the Indonesian side of Sebatik Island, adjacent to the international boundary.
A permanent base and training facility were established to support irregular warfare activities. These included the training, arming, and logistical support of North Kalimantan People's Army (NKPA) cadres and pro-Indonesian civilians from surrounding border settlements. This force constituted the nucleus of an irregular guerrilla network intended to complement conventional operations and conduct subversive actions within Malaysian territory.
Cross-border activity from these forward positions included regular harassment fire, reconnaissance-in-force missions, and the systematic mapping of Malaysian and Commonwealth defensive dispositions. Intelligence gathered was transmitted to Indonesian higher command to inform subsequent operational planning.
Aerial operations and preliminary bombardment
In support of the planned ground offensive and in an effort to secure local air superiority, the Indonesian Air Force deployed elements from the 4th, 11th, and 14th Air Squadrons to conduct aerial bombardment, escort, and deception operations. These missions targeted key military and logistical infrastructure in and around Tawau, with two primary objectives:
To degrade the combat effectiveness of Malaysian and Commonwealth forward units. To serve as a diversionary measure to obscure the infiltration of Indonesian ground elements across the border.
This aerial component was designed to disorient Commonwealth command-and-control structures and force the redeployment of Malaysian assets away from intended infiltration corridors.
Indonesian Air Assets Assigned: 4th Air Squadron – North American B-25 Mitchell medium bombers 11th Air Squadron – North American P-51D Mustang fighter aircraft 14th Air Squadron – Tupolev Tu-16KS-1 strategic bombers
These squadrons operated in coordination to execute precision strikes, provide fighter escort where necessary, and simulate broader offensive intent to mislead Commonwealth intelligence assessments and battlefield response.
Ground infiltration and main force advance
Indonesian main force elements were tasked with simultaneous multi-axis penetration of Sabah via two primary ingress routes: Eastern Axis: Via the Serudong River, with forces entering the Tawau District. Western Axis: Via the Tumalasak River near Nabawan District.
On the eastern axis, Indonesian ground forces comprised approximately 160 personnel, drawn from the Commando Operations Corps (KKO) and the North Kalimantan People's Army (NKPA), also known as the North Borneo Liberation Army. The primary objective of the eastern thrust was the capture of Tawau and Lahad Datu, to be followed by a continued advance northward toward Sandakan. Upon securing Sandakan, the plan called for Indonesian forces to consolidate their positions and await further operational directives from Jakarta.
This strategy reflected a phased escalation model, with subsequent actions contingent upon battlefield outcomes and local tactical conditions. The approach relied heavily on speed, local Sabahan support, and the disruption of Malaysian–Commonwealth defensive cohesion to achieve its strategic objectives.
Logistical considerations
Indonesian forces will brought military equipment from Kalimantan together with few days worth of food. During their operations inside Sabah, they were expected to get food help from anti-colonial resistance and pro-communist locals. They also expected to established logistical lines at Sabah east coast after liberating Tawau, Lahad Datu and Sandakan.
Battle Initial Indonesian action: Aerial bombardment phase
The engagement commenced on 7 December 1963 with aerial bombardment sorties conducted by the 14th Air Squadron of the Indonesian Air Force, utilising a Tupolev Tu-16KS-1 strategic bomber. The target of this initial strike was the town of Tawau, with the operational objective of disrupting Malaysian and Commonwealth defensive positions and facilitating the covert insertion of Indonesian ground forces.
A second aerial assault took place on 28 December 1963, this time executed by a B-25 Mitchell bomber of the 4th Air Squadron, escorted by two P-51D Mustang fighters from the 11th Air Squadron. The mission was part of a broader Indonesian strategy to degrade local command-and-control infrastructure and apply psychological pressure on defending forces.
Despite the intensity of these air raids, the bombings failed to strike any significant military targets. Instead, they caused damage to civilian structures in Tawau, though no casualties were reported on the Malaysian side. The aerial campaign, although limited in tactical effect, functioned as both a psychological warfare measure and a diversionary tactic to obscure the ongoing infiltration of Indonesian forces across the border.
Ground infiltration and movement to contact
Intelligence reports and recovered materials indicate that Indonesian ground elements likely entered Sabah between early and mid-December 1963. On 12 December, a Border Scouts patrol discovered abandoned enemy military equipment along the Tumalasak River, including: A metal container with 50 mm mortar rounds Three empty containers for .303 calibre ammunition Three pairs of Indonesian Armed Forces-issue boots Miscellaneous field items
On 20 December, a civilian report was received of a raid on a shop in Serudong Laut village by an armed group of approximately 10 personnel in green jungle uniforms bearing white insignia. The raiders abducted two Murut civilians, stole a radio set, and confiscated food supplies.
Subsequently, the enemy moved through Silimpopon, where gunfire was reported by local lumber workers—later attributed to wild boar hunting by Indonesian troops. The same elements bivouacked at a lumber camp near Kalabakan and then reorganised into four assault groups, as follows: DetachmentStrengthLeaderObjectiveN1~50Second Sergeant (Serda) Commando Corps (KKO) Rebani "Benny" and Hendrik (NKPA)Advance to KalabakanN237Serda KKO WayanAdvance toward TawauW134Serda KKO LasaniAdvance toward SandakanW230Serda KKO SubrotoAdvance toward Sandakan Kalabakan Incident
At 1900 hours on 29 December 1963, Detachment N1, under the command of Sergeant Rebani launched a coordinated surprise assault on a Commonwealth defensive outpost located approximately from the Indonesian-Malaysian border, near Kalabakan. The position was held by 1st Platoon, A Company, 3rd Battalion, Royal Malay Regiment (3 RMR).
The assault commenced with indirect fire, believed to be delivered by mortars or hand-thrown grenades, followed by a sustained small arms engagement. The firefight resulted in eight fatalities, including one officer, and eighteen personnel wounded, all from 3 RMR. Additionally, one civilian was killed and another seriously wounded during the exchange.