The Trucial Oman Scouts was a paramilitary force that the British raised in 1951 as the Trucial Oman Levies, to serve in the Trucial States. In 1956, the Levies were renamed the Trucial Oman Scouts. In 1971, the Scouts were renamed Union Defence Force (U.D.F.) upon the formation of United Arab Emirates (U.A.E.)
The Trucial Oman Scouts were established at Sharjah originally as the Trucial Oman Levies (TOL) in 1951. They were originally to be used as an internal security and rural gendarmerie, suppressing banditry and the slave trade, but became a military force after the arrival of a Saudi Arabian force in the Buraimi Oasis in September 1952. A British Army Major commanded the TOL, with the assistance of two Jordanian officers seconded from the Arab Legion. Its initial personnel consisted of 32 other ranks, also seconded from the Arab Legion. It was later expanded to 30 British officers in command positions, with a handful of Arab officers. It recruited its soldiers locally mostly from Abu Dhabi. There were also Yemeni soldiers assigned to the Trucial Oman Scouts from the Aden Protectorate Levies (APL), a British colonial militia based in South Yemen. It finally reached battalion strength.
In November 1952, some TOL soldiers were believed to be selling ammunition to the Saudis in Buraimi. Major Otto Thwaites, the commander of the TOL, went to Buraimi to investigate. There three Yemeni soldiers of the TOL shot him dead. A Jordanian Regimental Sergeant Major, Daud Sidqi, and an Royal Air Force doctor, Flying Officer A.L.C. Duncan, were also killed in the attack. The attack also wounded two British NCOs, Sergeant Chinn and Corporal Cruickshank, but they were able to drive away and get help. The three Yemeni soldiers who had carried out the attack fled to Saudi Arabia, but were eventually returned to Sharjah to stand trial after the intervention of His Highness Sheikh Zayed bin Sultan Al Nahyan of Abu Dhabi. The shootings revealed a key weakness in not screening the Yemeni soldiers from the APL before they joined the Trucial Oman Levies.