Brunei became a British protectorate in 1888, had an area of about 2,226 square miles (5,800 km2) and some 85,000 people.

Oil was discovered in 1929 near Seria and the Shell Petroleum Company concession provided the Sultanate with a huge income.

In 1959, the Sultan, Sir Omar Ali Saifuddin III, established a legislature with half its members nominated and half elected.

Elections were held in September 1962 and all of the contested seats were won by the Brunei People’s Party.

Hints of brewing trouble came in early November 1962 when the Resident for the 5th Division of Sarawak, Richard Morris (an Australian), who was based in Limbang (sandwiched between the two parts of Brunei) received information. Special Branch police from Kuching visited Limbang but only found some illegal uniforms with TNKU badges.

On 6 December, Morris heard the rebellion would start on the 8th. On 7th, similar information reached John Fisher, the resident of the 4th Division of Sarawak, based in Miri some 20 miles (30 km) west of Brunei. As a result, police were put on full alert through Brunei, North Borneo and Sarawak, and Police Field Force reinforcements were flown from Kuching to Miri.

The rebellion broke out at 2:00 am on 8 December. Signals from Brunei to British Far East Headquarters reported rebel attacks on police stations, the Sultan’s Istana, the Prime Minister’s house and the power station, and that another rebel force was approaching the capital by water. Far East Headquarters ordered ALE YELLOW, which placed a force of two Gurkha infantry companies on 48 hours notice to move.

By five in the morning, TNKU controlled Pekan Besar. News came that a number of civil servants at Pekan Besar had managed to escape capture. Around an hour later at downtown, the Deputy Chief Minister was granted an audience by the Sultan. After the meeting, the Sultan made a radio declaration condemning TNKU, the armed wing of the Brunei People's Party, for treason.

Nine hours after ALE YELLOW, ALE RED was ordered and two companies of 1st Battalion, 2nd Gurkha Rifles, of 99th Infantry Brigade, moved to the RAF airfields at Changi and Seletar in Singapore to fly to Labuan Island in Brunei Bay. The Beverleys landed at about 10:00 pm and the Gurkhas advanced into Brunei. They fought a series of actions, suffering six casualties, two fatal. A small group of Gurkhas led by Captain Digby Willoughby rescued the Sultan and took him to police headquarters. An advance to Seria met strong opposition and returned to Brunei to counter a rebel threat to its centre and the airfield.

On 9 December, John Fisher called on the Dayak tribes for help by sending a boat with the traditional Red Feather of War up the Baram River. Tom Harrisson, the Curator of the Sarawak Museum in Kuching and leader of resistance to the Japanese in the Second World War also arrived in Brunei. He summoned the Kelabits from the highlands around Bario in the 5th Division, the centre of his wartime resistance. Hundreds of Dayaks responded, and formed into companies led by British civilians all commanded by Harrison. This force reached some 2,000 strong, and with excellent knowledge of the tracks through the interior (there were no roads), helped contain the rebels and cut off their escape route to Indonesia.

On 10 December, a company of the Queen’s Own Highlanders boarded five Twin Pioneers and a Beverley at Brunei. The Twin Pioneers landed west of Seria and the Beverley at Anduki. A police station 2 miles (3 km) from the western landing was recaptured and so was the Telecommunications Centre after a brief fight. Anduki airfield was quickly recaptured. However, the main Seria police station, with 48 hostages, most Shell expatriates, was not secured until the 12th.

On 10 December, the Far East ‘spearhead battalion’, the Queen’s Own Highlanders began arriving in Brunei. Brigadier Patterson, commander 99th Gurkha Infantry Brigade arrived to take overall command from Brigadier Pat Glennie, normally the Brigadier General Staff at Far East HQ. Both reported to Lieutenant General Sir Nigel Poett, the Far East Land Forces Commander in Singapore. Seria and Limbang remained in rebel hands. Further reinforcements arrived in the following days.

Eighty-nine Marines of 42 Commando had arrived in Brunei on 11 December, led by Captain Jeremy Moore (who later commanded the British Forces during the Falklands War).

After acquiring two landing craft, the Marines were transported to Limbang by Royal Navy crews led by Captain Black (who later commanded HMS Invincible during the Falklands War) and staged their arrival at dawn, 13 December.

On 14 December, most of the unit reinforced the artillery battery sent there as infantry on 12 December to pre-empt trouble from the Chinese of the Clandestine Communist Organisation (CCO) who were openly sympathetic to the Brunei rebels.

By 17 December, the rebellion had been held and broken. Some 40 rebels were dead and 3,400 captured. The remainder had fled and were assumed to be trying to reach Indonesia. Of the leaders, Azahari was in the Philippines and Yassin Affendi was with the fugitives.

By 17 December 42 Commando was complete in Brunei and 1st Green Jackets (43rd and 52nd) had landed from the cruiser HMS Tiger in Miri. 40 Commando aboard the commando carrier HMS Albion was diverted from Miri to Kuching.

On 12 April, the police station at Tebedu in the 1st Division of Sarawak was attacked and captured. The attackers had come from Kalimantan. This marked the beginning of Confrontation.

On 18 May, a patrol of 1/7 Gurkhas were guided by an informer to a camp in the mangrove. They flushed a party of rebels towards an ambush. Ten rebels were killed or captured. They were the remnants of TNKU headquarters and one of the wounded, shot in the hip, was Yassin Affendi.