The Singapore strategy was a naval defence policy of the United Kingdom that evolved in a series of war plans from 1919 to 1941. It aimed to deter aggression by Japan by providing a base for a fleet of the Royal Navy in the Far East, able to intercept and defeat a Japanese force heading south towards India or Australia. To be effective it required a well-equipped base. Singapore, at the eastern end of the Strait of Malacca, was chosen in 1919 as the location of this base; work continued on this naval base and its defences over the next two decades.
The planners envisaged that a war with Japan would have three phases: while the garrison of Singapore defended the fortress, the fleet would make its way from home waters to Singapore, sally to relieve or recapture Hong Kong, and blockade the Japanese home islands to force Japan to accept terms. The idea of invading Japan was rejected as impractical, but British planners did not expect that the Japanese would willingly fight a decisive naval battle against the odds. Aware of the impact of a blockade on an island nation at the heart of a maritime empire, they felt that economic pressure would suffice.
The Singapore strategy was the cornerstone of British Imperial defence policy in the Far East during the 1920s and 1930s. By 1937, according to Stephen Roskill, "the concept of the 'Main Fleet to Singapore' had, perhaps through constant repetition, assumed something of the inviolability of Holy Writ". A combination of financial, political and practical difficulties ensured that it could not be successfully implemented. During the 1930s, the strategy came under sustained criticism in Britain and abroad, particularly in Australia where the Singapore strategy was used as an excuse for parsimonious defence policies. The strategy ultimately led to the despatch of Force Z to Singapore and the sinking of the Prince of Wales and Repulse by Japanese air attack on 10 December 1941. The subsequent ignominious fall of Singapore was described by Winston Churchill as "the worst disaster and largest capitulation in British history".
Origins After the First World War, the Imperial German Navy's High Seas Fleet that had challenged the Royal Navy for supremacy was scuttled in Scapa Flow. However, the Royal Navy was already facing serious challenges to its position as the world's most powerful fleet from the United States Navy and the Imperial Japanese Navy. The United States' determination to create what Admiral of the Navy George Dewey called "a navy second to none" presaged a new maritime arms race.
The U.S. Navy was smaller than the Royal Navy in 1919 but ships laid down under its wartime construction programme were still being launched and their more recent construction gave the American ships a technological advantage. The two-power standard of 1889 called for a Royal Navy strong enough to take on any two other powers. In 1909, this was reduced to a 60% superiority in dreadnoughts.
Rising tensions over the U.S. Navy's building programme led to disputes between the First Sea Lord, Admiral Sir Rosslyn Wemyss and the Chief of Naval Operations Admiral William S. Benson in March and April 1919, although, as far back as 1909, the government directed that the United States was not to be regarded as a potential enemy. This decision was reaffirmed by Cabinet in August 1919 to preclude the U.S. Navy's building programme from becoming a justification for the Admiralty initiating one of its own. In 1920, the First Lord of the Admiralty Sir Walter Long announced a "one-power standard", under which the policy was to maintain a navy "not ... inferior in strength to the Navy of any other power". The one-power standard was promulgated at the 1921 Imperial Conference.
The Prime Ministers of the United Kingdom and the Dominions met at the 1921 Imperial Conference to determine a unified international policy, particularly the relationship with the United States and Japan. The most urgent issue was that of whether or not to renew the Anglo-Japanese Alliance, which was due to expire on 13 July 1921. The Prime Minister of Australia Billy Hughes and the Prime Minister of New Zealand Bill Massey, strongly favoured its renewal. Neither wanted their countries to be caught up in a war between the United States and Japan and contrasted the generous assistance that Japan rendered during the First World War with the United States' disengagement from international affairs in its aftermath. "The British Empire", declared Hughes, "must have a reliable friend in the Pacific". They were opposed by the Prime Minister of Canada, Arthur Meighen, on the grounds that the alliance would adversely affect the relationship with the United States, which Canada depended upon for its security. No decision to renew was reached, and the alliance was allowed to expire.
The Washington Naval Treaty in 1922 provided for a 5:5:3 ratio of capital ships of the British, United States and Japanese navies. Throughout the 1920s, the Royal Navy remained the world's largest navy, with a comfortable margin of superiority over Japan, which was regarded as the most likely adversary. The Washington Naval Treaty also prohibited the fortification of islands in the Pacific except for Singapore. The provisions of the London Naval Treaty of 1930 restricted naval construction, resulting in a serious decline in the British shipbuilding industry. German willingness to limit the size of its navy led to the Anglo-German Naval Agreement of 1935. This was seen as signalling a sincere desire to avoid conflict with Britain. In 1934, the First Sea Lord, Admiral Sir Ernle Chatfield, began to press for a new naval build-up sufficient to fight Japan and the strongest European power. He intended to accelerate construction to the maximum capacity of the shipyards but the Treasury soon became alarmed at the potential cost of the programme of £88 to £104 million. By 1938, the Treasury was losing its fight to stop rearmament; politicians and the public were more afraid of being caught unprepared for war with Germany and Japan than of a major financial crisis in the more distant future.
Plans
The Singapore strategy was a series of war plans that evolved between the wars in which the basing of a fleet at Singapore was a common but not a defining aspect. Some plans were designed to defeat Japan, while others were to deter aggression. In November 1918, the Australian Minister for the Navy, Sir Joseph Cook, had asked Admiral Lord Jellicoe to draw up a scheme for the Empire's naval defence. Jellicoe set out on a tour of the Empire in the battlecruiser in February 1919. He presented his report to the Australian government in August 1919. In a confidential section of the report, he advised that the interests of the British Empire and Japan would inevitably clash. He called for the creation of a British Pacific Fleet strong enough to counter the Imperial Japanese Navy, which he believed would require 8 battleships, 8 battlecruisers, 4 aircraft carriers, 10 cruisers, 40 destroyers, 36 submarines and supporting auxiliaries.
Although he did not specify a location, Jellicoe noted that the fleet would require a major dockyard somewhere in the Far East. A paper entitled "The Naval Situation in the Far East" was considered by the Committee of Imperial Defence in October 1919. In this paper the naval staff pointed out that maintaining the Anglo-Japanese Alliance might lead to war between the British Empire and the United States. In 1920, the Admiralty issued War Memorandum (Eastern) 1920, instructions in the event of a war with Japan. In it, the defence of Singapore was described as "absolutely essential". The strategy was presented to the Dominions at the 1923 Imperial Conference. The authors of the memorandum divided a war with Japan into three phases. In the first phase, the garrison of Singapore would defend the fortress while the fleet made its way from home waters to Singapore. The fleet would sail from Singapore and relieve or recapture Hong Kong. The final phase would see the fleet blockade Japan and force it to accept terms.
Most planning focused on the first phase, which involved the fortification of Singapore. For the second phase, a naval base capable of supporting a fleet was required. While the United States had constructed a graving dock capable of taking battleships at Pearl Harbor between 1909 and 1919, the Royal Navy had no such base east of Malta. In April 1919, the Plans Division of the Admiralty produced a paper which examined possible locations for a naval base in the Pacific in case of a war with the United States or Japan. Hong Kong was considered but regarded as too vulnerable, while Sydney was regarded as secure but too far from Japan. Singapore emerged as the best compromise location.
Estimates of the time for the fleet to reach Singapore after the outbreak of hostilities varied. It had to include the assembly of the fleet, preparations for the voyage and transit to Singapore. The first estimate was 42 days, assuming reasonable warning. In 1938, it was increased to 70 days, with 14 more for provisioning. It was further increased in June 1939 to 90 days plus 15 for provisioning and in September 1939, to 180 days.
Oil storage facilities were constructed at Gibraltar, Malta, Port Said, Port Sudan, Aden, Colombo, Trincomalee, Rangoon, Singapore and Hong Kong. A complicating factor was that the battleships could not traverse the Suez Canal fully laden, so they would have to refuel on the other side. Singapore was to have storage for of oil. Secret bases were established at Kamaran Bay, Addu Atoll and Nancowry. It was estimated that the fleet would require of oil per month, which would be transported in sixty tankers. Oil would be shipped in from the refineries at Abadan and Rangoon, supplemented by buying the entire output of the Netherlands East Indies.
The third phase received the least consideration but naval planners were aware that Singapore was too far from Japan to provide an adequate base for operations near Japan. The further the fleet proceeded from Singapore, the weaker it would become. If American assistance was forthcoming, there was the prospect of Manila being used as a forward base. The idea of invading Japan and fighting its armies was rejected as impractical but the British planners did not expect that the Japanese would willingly fight a decisive naval battle against the odds. They were therefore drawn to the concept of a blockade; from experience they were aware of the impact it could have on an island nation at the heart of a maritime empire and felt that economic pressure would suffice.
Japan's vulnerability to blockade was studied; with information from the Board of Trade and the naval attaché in Tokyo, the planners estimated that the British Empire accounted for around 27 per cent of Japan's imports. In most cases these imports could be replaced from sources in China and the United States. Some critical materials for which Japan relied heavily on imports were identified, including metals, machinery, chemicals, oil and rubber and many of the best sources were under British control. Japanese access to neutral shipping could be restricted by refusing insurance to ships trading with Japan and by chartering ships to reduce the number available.