This was a British unrealised plan by Air Chief Marshal Sir Robert Brooke-Popham, commander-in-chief Far East Command, for an advance by some of the British forces in Malaya to occupy the area of Singora and Patani in southern Thailand should the Japanese move into that country, and thus be in a better strategic position to counter any Japanese amphibious invasion of Malaya (August 1941).
In 1937 Major General W. G. S. Dobbie, commanding in Malaya, had reported that during the monsoon season from October to March an enemy could effect landings on the east coast of Thailand and then establish bases in that country, and predicted that such landings could be made at Songkhla and Patani in south-eastern Thailand, and at Kota Bharu in north-eastern Malaya. Dobbie recommended the immediate despatch of considerable reinforcements to Malaya, but his recommendation was ignored.
After assuming command of the Far East Command, Brooke-Popham looked again at the defences of Malaya and saw the strategically sense of a British occupation of portions of the narrow Isthmus of Kra as a good natural defence against Japanese movement south into Malaya. Brooke-Popham therefore submitted to London his ‘Matador’ (i) plan. This was based on the assumption that the Japanese would land on the east coast of Thailand at Singora and Patani, then advance to the south in the direction of Jitra and Kroh just inside the Malayan border.
‘Matador’ (i) envisaged the establishment of two forces to intercept the advancing Japanese just over the border in Thailand and then hold them long enough for the main British force to assemble in northern Malaya and counterattack.
There were several problems with the plan, however. In January 1941 a request for additional resources remained unfulfilled, and in 1940 Sir Josiah Cosby, the British ambassador in Thailand, had signed a non-aggression pact with Field Marshal Plaek Phibunsongkhram, the prime minister and virtual dictator of Thailand.
On 5 December 1941, when the threat of Japanese invasion became more likely, the plan was modified to use the forces available and to be implemented as soon as an attack seemed imminent. 'Matador' (i) was now based on the assumption that if an enemy attacked, or was invited into, Thailand, British troops would move swiftly to Singora and defend it against a seaborne landing: Singora was the only port with the capacity to supply between three and four Japanese divisions, and its occupation by the British would seriously hamper any Japanese move to the south as the aggressor would be denied the use not only of the port but also of the airfields in the region as well as the main road and the railway.
Brooke-Popham believed that a British occupation of this strategically key area by three brigade groups, four bomber squadrons and two fighter squadrons would limit any Japanese invasion to a single division which would have to be supplied, and only with great difficulty, overland from Bangkok and threatened by British aircraft operating from Singora and Patani.
This task was allocated to Major General D. M. Murray-Lyon’s Indian 11th Division of Lieutenant General Sir Lewis Heath’s Indian III Corps, which was also to defend Jitra. In realistic terms, however, this was a task considerably greater than could realistically be undertaken by a single division.
On 5 December London signalled its permission for Brooke-Popham to decide if and when ‘Matador’ (i) should be activated. The primary strategic decision to be made was whether or not Thailand should be ‘invaded’ in a pre-emptive move before any Japanese landings had taken place. The Malaya Command was responsible for the detailed planning of ‘Matador’ (i), and by 6 December had reworked the plan and allocated the forces for immediate deployment. Lieutenant General A. E. Percival, commanding in Malaya, made his recommendation during the evening of the same day at a meeting with the governor, Sir Shenton Thomas, and Brooke-Popham, and it was decided that it would be premature to launch an operation which included any pre-emptive move into Thailand.
The Japanese then pre-empted ‘Matador’ (i) with their own 'E' (i) landings at Singora and Patani by Lieutenant General Takuro Matsui’s 5th Division and Lieutenant General Renya Mutaguchi’s 18th Division, exactly as had been forecast, on 8 December 1941.
With hindsight it is possible to see that the British had reached the wrong decision, but even if ‘Matador’ (i) had been implemented, the Japanese had developed a counter to it: they would use Bangkok airport and the airfields of southern Thailand to provide air cover and then invade from the Isthmus of Kra.