The Raid on Kalabakan, also referred to in Malaysia as the Kalabakan Incident (), was a military operation conducted by Indonesian forces, supported by communist guerrilla fighters, during the Battle of Tawau in the wider context of the Indonesia–Malaysia Confrontation. The primary objective of the raid was the capture of Kalabakan, intended as the initial step in a broader offensive. The planned follow-on phases included an advance on Tawau town, continued movement toward Lahad Datu, and ultimately the seizure of Sandakan in the north.

Geography At the time of the Indonesia–Malaysia Confrontation, Kalabakan, then known as Kampung Kalabakan (Kalabakan Village), was a rural settlement located in the rainforest interior of the Tawau Division, Sabah, Malaysia. The village lay approximately north-west of Tawau town and about from the Indonesia–Malaysia border, occupying a strategic position along the Kalabakan River—a vital transportation artery for both civilian and commercial activities.

By the early 1930s, Kalabakan had developed into a significant economic settlement. This growth was primarily attributed to the expansion of rubber, cocoa, tea, oil palm, and hemp plantations, in conjunction with the development of the timber industry. The largest industrial operation within the area was conducted by North Borneo Timbers, a subsidiary of the Bombay Burmah Trading Corporation.

The Kalabakan River served as the primary access route from Tawau, extensively utilising it for industrial transport and the downstream movement of logs to timber processing facilities located within the village. The surrounding area was characterised by hilly terrain and dense jungle, which presented both natural concealment and operational challenges for military activity.

At the time of the Kalabakan raid, the village's defences consisted of a fortified outpost, which concurrently functioned as the local police station. A military outpost had been recently established in the vicinity, approximately from the police post. This deployment was a direct response to an increase in cross-border incursions, indicating a heightened state of alert during the confrontation.

Background The Indonesia–Malaysia Confrontation was an armed conflict initiated by the Republic of Indonesia in January 1963, in opposition to the formation of the Federation of Malaysia. Under the leadership of President Sukarno, Indonesia framed Malaysia's creation as a neocolonial construct, allegedly orchestrated by the United Kingdom to preserve Western influence in Southeast Asia. Beyond ideological opposition, the confrontation also reflected Jakarta's longstanding ambition—dating back to the 1950s—to realise a "Greater Indonesia" (Indonesia Raya), encompassing all Malay-speaking territories, including Malaya, Sabah and Sarawak.

In response to escalating tensions, the disused Second World War-era Japanese military base in Tawau was reactivated and repurposed as a defensive stronghold. A combined Malaysian and Commonwealth security force was established, with the East Sabah Brigade assigned responsibility for the defence of East Sabah, including the Tawau Division (then known as Tawau Residency).

For the Tawau Residency, military units deployed to the region included elements from the 10th Gurkha Rifles, the 3rd Battalion, Royal Malay Regiment (3 RMR), the 1st Battalion, King's Own Yorkshire Light Infantry (KOYLI), and the 2nd Regiment Federation Reconnaissance (present-day 2nd Regiment, Royal Armoured Corps). Platoons from these units were strategically distributed to facilitate monitoring and response to potential incursions.

In Kalabakan, a wooden structure on a hill—originally owned by North Borneo Timbers—was offered to the Malaysian authorities for military use. The building was fortified and repurposed as a forward outpost. The 1st Platoon, A Company, 3 RMR, was the first sub-unit assigned to the site, later reinforced by the 10th Platoon, C Company, 3 RMR, to bolster the outpost's defensive capacity.

The Raid on Kalabakan formed a key component of the broader Battle of Tawau. Leading up to the engagement, Indonesian forces conducted an aerial bombardment of Tawau on 7 December 1963, followed by ground infiltration operations. Infiltration elements consisted of elite Commando Operations Corps ( – KKO) personnel—precursors to the present-day Indonesian Marine Corps—as well as communist guerrilla fighters from the North Kalimantan People's Army (NKPA), the armed wing of the North Kalimantan Communist Party.

Infiltration occurred between early and mid-December 1963, with Indonesian forces entering Sabah via Serudong Laut Village and passing through Silimpopon before reaching Kalabakan. Upon arrival in Kalabakan, the force were divided into four detachments, each assigned distinct operational objectives intended to maximise territorial disruption and facilitate a multi-pronged advance: DetachmentLeaderObjectiveN1Commando Corps (KKO) Second Sergeant (Serda) Rebani aka Benny, and Hendrik (NKPA)Advance to KalabakanN2KKO Serda WayanAdvance toward TawauW1KKO Serda LasaniAdvance toward SandakanW2KKO Serda SubrotoAdvance toward Sandakan

Indonesian tactical plan for Kalabakan Detachment N1, comprising approximately 45–50 personnel—including 31 KKO commandos and the remainder from the NKPA—was tasked with capturing Kalabakan. The detachment was led by Second Sergeant (Serda) Rebani of the KKO and supported by Hendrik of the NKPA.

To maximise the effectiveness of the assault, Serda Rebani divided his detachment into three assault groups, with orders to surround the Kalabakan military outpost and conduct a night attack under blackout conditions. Each group was assigned a sector of approach: Assault Group 1 (Led by KKO Corporal Sukibat): Tasked with moving off the ridge to target the police outpost from the north. Assault Group 2 (Led by KKO Second Sergeant Rebani): Tasked with ascending the hill north of the military outpost and moving downhill to target the military outpost from the rear. Assault Group 3 (Led by KKO Private Asmat): Tasked with climbing the hill, moving west, and conducting a resupply operation within Kalabakan Village.

Following the capture of Kalabakan, Detachment N1 was to link up with Detachment N2, which had taken up a concealed position near Tawau, to initiate the next phase of operations: the seizure of Tawau, followed by advances on Lahad Datu and Sandakan.

Malaysian strategy Fortification of Kalabakan

Upon deployment to Kalabakan, Malaysian forces undertook immediate steps to fortify their position. Three defensive sandbag forts were constructed around a wooden structure provided by North Borneo Timbers, originally built as accommodation for mill workers. The building was repurposed to serve as a command post and weapons storage facility for both military personnel and North Borneo Timbers.

The fortified site was designated Kalabakan Base Camp (), strategically positioned facing the Kalabakan River to monitor and defend against potential infiltration by enemy forces approaching via the waterway.

Deployment considerations: Serudong Laut Village

Shortly before the Kalabakan engagement, the police report regarding an Indonesian raid on a civilian store in Serudong Laut Village reached Captain Zainol Abidin Yaacob, commanding officer of Kalabakan Base Camp.

At the time, Captain Zainol was attending a coordination meeting with local police personnel at his field quarters, located near the Kalabakan Police Station in the centre of the village. Accompanied by his personal aide, Private Ismail Mat, the meeting addressed plans to deploy a military presence to Serudong Laut Village, which lay approximately from the Indonesia–Malaysia border.

Up to that point, Serudong Laut had only been patrolled and defended by the Police Field Force's Border Scouts, with no regular army presence stationed in the area. The proposed deployment aimed to strengthen the frontier's defensive posture in light of escalating cross-border threats.

Battle According to Mail@Gading Malonti, a member of the Police Field Force who was present during the events, the Indonesian raid on Kalabakan began at approximately 2000 hours on 29 December 1963, shortly after the Isha prayer call. The first indication of the assault was the sound of small-arms fire, followed by a loud explosion emanating from the direction of the Kalabakan Police Station. Believing an incident had occurred at the police post, Captain Zainol Abidin Yaacob, accompanied by his aide, Private Ismail Mat, and Constable Mail, proceeded on foot towards the police station to render assistance.

Unbeknownst to them, the initial gunfire had originated from the direction of the Kalabakan Base Camp, not the police station. While advancing using a torchlight, both Captain Zainol and Private Ismail were ambushed and killed instantly by Indonesian fire. Constable Mail managed to evade incoming rounds and took cover, eventually reaching the Kalabakan Police Station safely by crawling and rolling through cover.

At the time, the police station was staffed by one regular police officer and six Vigilante Corps home guards. Upon hearing the gunfire, the remainder of the station's personnel—eight police officers, including a police corporal commanding officer, and 20 home guards—rapidly mobilised and assembled at the outpost.

Simultaneously, at Kalabakan Base Camp, Second Lieutenant Raja Shaharudin Raja Rome, the second-in-command of the outpost, was on duty and present at the command post with 38 personnel. He reported initially hearing a series of gunshots that appeared to be targeting other areas. Moments later, the base came under intense enemy fire. He immediately moved by crawling into one of the fortified positions but was unable to visually identify the attackers due to complete darkness. The only visible light source in the vicinity was from the base camp itself, which inadvertently illuminated their position and rendered the defenders vulnerable to incoming fire.

The base came under sustained assault, with enemy grenades and possible mortar fire impacting their defences. The lack of visibility made coordinated return fire extremely difficult, and the defenders were largely pinned down throughout the engagement.

Approximately from the military base, the Kalabakan Police Station faced similar conditions. In response to visible enemy muzzle flashes, the police personnel opened fire in the general direction of the attackers. At approximately 2010 hours, the Indonesian assault intensified on the police outpost. However, owing to its older construction and more robust fortifications, the police station held firm. Despite repeated attempts, the Indonesian forces failed to overrun the police defences.

The firefight continued at both positions until approximately 2300 hours, after which the intensity of enemy fire began to decrease. At that point, Mr Ress, the branch manager of North Borneo Timbers in Kalabakan, arrived at the military base with one of his employees and offered to assist in organising a pursuit party. However, due to heavy casualties and disorganisation among the defenders, no immediate pursuit was undertaken.

While the primary engagement ceased around 2300 hours, sporadic gunfire continued until 0300 hours. It is believed these random shots were intended to discourage pursuit and conceal the withdrawal of Indonesian forces from the Kalabakan area.

Casualties

Indonesian side On the Indonesian side, casualties were recorded as one killed in action and three wounded. The fallen Indonesian soldier was killed near the police outpost. +Killed in action (Indonesia)RankNameUnitPrivate (KKO) or MarineGabriel1st Bn, Commando Operations Corps

Malaysian-Commonwealth side