Singapore Naval Base

His Majesty's Naval Base, Singapore, also Her Majesty's Naval Base, Singapore (HMNB Singapore), alternatively known as the Singapore Naval Base, Sembawang Naval Base and HMS Sembawang, was situated in Sembawang at the northern tip of Singapore and was both a Royal Navy shore establishment and a cornerstone of British defence policy (the Singapore strategy) in the Far East between the World Wars. From 1921 to 1941 it was a China Station base, from 1941 to 1945 a repair facility for the Imperial Japanese Navy (IJN), and from 1945 to 1958 a Far East Fleet base. Today, it is a commercial dockyard but British military activity still exists at the British Defence Singapore Support Unit (BDSSU).

Through the 19th century, the British Government relied on four Imperial fortress colonies as primary bases for the Royal Navy and British Army for control of the World's oceans. These were Bermuda and Halifax, Nova Scotia (military control of the latter was handed to the Canadian militia following Canadian Confederation in 1867, and naval control to the Royal Canadian Navy after 1905, along with Esquimalt Royal Naval Dockyard, which had been the main base of the Pacific Station), in the North Atlantic, and Gibraltar and Malta. As it was presumed that the only navies that could challenge the Royal Navy were those of European powers, no base equivalent to an Imperial fortress had been constructed outside of the Atlantic and its connected seas. This was despite the growing threats of the Pacific fleets of the Russian Empire and the United States during the late 19th Century. After the Great War, the British Government devoted significant resources into building a naval base on Singapore Island, where the capital of the Straits Settlements was located, as a deterrent to the increasingly ambitious Japanese Empire with its growing fleet. Britain lacked a naval 'Imperial fortress' in the broad region of Asia, the Indian Ocean, and the Pacific Ocean. Instead, the British Empire relied on the squadron of the Bermuda based America and West Indies Station, utilising the Panama Canal after its 1914 completion, to patrol the western Atlantic and the eastern Pacific, while vessels based in Malta in the Mediterranean Sea could project naval and military force to the Indian and western Pacific oceans via the Suez Canal, which had been completed in 1869. In light of the rising threat of the Imperial Japanese Navy (IJN), this was no longer adequate.

Originally announced in 1923, the construction of the base proceeded slowly at Sembawang until the Japanese invasion of Manchuria in 1931. It was completed in 1938, at a staggering cost of £60 million – equivalent to £2½ billion in 2006. The base covered 21 square miles (54 km²) and had what was then the largest dry dock in the world, the third-largest floating dock, and enough fuel tanks to support the entire Royal Navy for six months.

It was defended by 15-inch naval guns stationed at Johore battery, Changi, and at Buona Vista Battery. Other important batteries of smaller calibre were located at Fort Siloso, Fort Canning, and Labrador. Air defence relied on the Royal Air Force (RAF) airfields at RAF Tengah and RAF Sembawang.

Winston Churchill touted it as the "Gibraltar of the East".

The base was renamed from HMS Terror to HMS Sultan on 1 January 1940 to acknowledge the proximity of the nine sultanates on the Malay Peninsula.

After the fall of Malaya on 31 January 1942, Singapore came within range of the artillery guns of the Twenty-Fifth Army of the Imperial Japanese Army (IJA), who were positioned in Johor within sight of the base. The IJA was poised to capture Singapore within a fortnight. The base was subsequently captured, largely intact, by units of the advancing IJA and became the IJN No. 101 Repair Facility through to the end of the Second World War, during which time it was used by all 3 Axis powers. It was used by Italian cargo-carrying submarines until the Italian Armistice, and by German cargo-carrying submarines until the German surrender.

With the surrender of Japan in August 1945, control of the naval base and Singapore was reverted to British and Commonwealth Forces in September 1945, when allied units of South East Asia Command under Lord Louis Mountbatten started to arrive in Singapore.