In 1921 it was decided to build a naval base at Singapore, and all subsequent defence arrangements hinged on its protection against attack by sea, air, or land. The base itself was to be located on the north shore of Singapore Island, facing out on to the Johore Strait, which was the naval anchorage.
At that time, and for many years to come, it was considered that the security of the base depended ultimately on the ability of the British Fleet to control the sea approaches to Singapore. As soon as it arrived it would deal with any Japanese sea forces in the vicinity and cut the communications of any land or air forces that might have installed themselves in the neighbourhood. It was the duty of the land and air forces of the garrison to hold off the enemy forces until the British came. This period, "the period before relief", was first estimated at seventy days, it being assumed that the enemy forces started from Japan, since at the time Japan had not begun to expand into China and beyond. With such a relatively short time available to them before the arrival of our Fleet, the most likely form of Japanese attack was held to be a coup de main direct on the island. Defences were planned accordingly and only a comparatively small garrison was needed.
The international situation in the nineteen-twenties did not necessitate costly outlay on modernising the defences, and it was not until 1933, after Japan had withdrawn from the League of Nations, that the Cabinet decided to take active steps.
By now developments in air-power greatly affected the defence problem. Singapore was exposed to carrier-borne attacks and to shore-based aircraft from ever-increasing ranges. Our own aircraft, too, could reconnoitre and strike further afield. Hitherto the only R.A.F. aerodrome had been on Singapore Island. Two more aerodromes were constructed there, and work began on others on the east coast, eventually as far north as the frontier of Siam. This was a new commitment for the Army. Not only had the Army to protect these aerodromes for our own use, but it also had to ensure that the enemy was denied the use of them for launching attacks on the naval base. In this connection there was friction between the authorities, due to a tendency to site airfields from the point of view of operational flying and with little regard to their ground defence. In any case, it was obviously not only wasteful but positively dangerous to make new airfields unless there was a reasonable certainty of a strong and efficient Air Force to use them and to co-operate in the defence as a whole.
In 1937 the general position was again fully reviewed, and an assessment made of defence requirements based on two main assumptions:
- that any threat to our interests would be seaborne;
- that we should be able to send to the Far East within threemonths a fleet of sufficient strength to protect the Dominions and India and give cover to our communications in the Indian Ocean.
In essence there was little change between the view taken in 1937 and that of 1921, but in 1939 the "period before relief" was raised to one hundred and eighty days, authority was given for reserves to be accumulated on the extended scale, and a reinforcing infantry brigade was sent from India.
The consequences of the first year of the war completely altered the outlook. Principal among these were the Japanese advance into Southern China and Hainan; the situation in Indo-China resulting from the French collapse; the increased range of aircraft; above all, the necessity for retaining in European waters a fleet of sufficient strength to match both the German and Italian Fleets, so making it impossible for us to send to the Far East an adequate naval force should the need for it arise.
In August 1940 the Chiefs of Staff reviewed the position. Their main conclusions were:
- Until Germany and Italy were defeated, or drastically reduced in naval strength, we were faced with the problem of defending our Far Eastern interests without an adequate fleet. Our object must be to limit the extent of inevitable damage, and at least to retain a footing from which we could eventually retrieve the position when stronger forces became available,
- It was no longer sufficient to concentrate upon the defence of Singapore Island; it was now necessary to hold the whole of Malaya. This involved an increase in the existing army and air forces.
- In the absence of a fleet our policy should be to rely primarily on air-power. The necessary air forces could not be provided for some time; until then substantial additional land forces were needed.
- Our naval building programmes have never allowed for a war in which we alone fought Germany, Italy, and Japan. The best hope of being able to supply naval forces in the Far East lay in the possibility of early and successful action against Italian naval forces in the Mediterranean.
In August 1940 the air force in Malaya numbered eighty-four first-line aircraft. The Chiefs of Staff considered, subject to the views of local commanders, that 336 first-line aircraft were required in the Far East (including fifty-four aircraft for trade protection in the Indian Ocean) to meet the new responsibilities placed upon the Royal Air Force.
A conference assembled at Singapore in October 1940 recommended that the figure of 336 should be raised to 582. The Air Ministry considered this far beyond the bounds of practical possibility; the Chiefs of Staff agreed that 582 was an ideal, but considered that 336 should give a fair degree of security.
On December 7, 1941, the strength of the R.A.F. in Malaya was 158 aircraft (of which twenty-four were obsolete Wildebeestes). Authorised reserves for this first-line strength were 157; actual reserves held were eighty-eight.
In August 1940 the Army garrison in Malaya, apart from coast defence, A.A., and auxiliary troops, consisted of nine battalions and one mountain artillery brigade.
The Chiefs of Staff further recommended that when the Royal Air Force had reached the figure they advised (336) the minimum garrison should be six brigades (eighteen battalions), with ancillary troops. In January 1941, on the advice of G.O.C. Malaya, this was raised by the Chiefs of Staff to twenty-six battalions. But until the Air Force was able adequately to undertake its responsibilities they considered the garrison should be increased by the equivalent of three divisions; total garrison would thus be nine plus twenty-seven equals thirty-six battalions, with ancillary troops.
In August 1941 General Percival put forward a new proposal in which the battalion strength amounted to forty-eight. This was accepted by the Chiefs of Staff, but it was recognised that it could not be met in the foreseeable future.
On December 7, 1941, the Army strength in Malaya (apart from coast defence and A.A.) was:
32 battalions, 7 field artillery regiments,
1 mountain artillery regiment,
2 anti-tank artillery regiments.
The above numbered 76,300 men (there were no tank units).
Although the War Office, but not General Percival's, target was thus nearly achieved, some of the troops recently arrived from India were raw and their fighting quality was low. Three of the artillery regiments arrived less than a month before the outbreak of hostilities, and had had little opportunity to train with other arms in the peculiarities of jungle warfare.