CEYLON, an island with a mixed-race population of about 6.2 million people at the time of the Second World War, was annexed by Britain because of its strategic importance during the Revolutionary and Napoleonic Wars (1792–1815). Left in Dutch hands, the risk of French corsairs using Colombo and Trincomalee as bases to intercept British shipping in the Indian Ocean was too great, and so these key ports were occupied. Ceylon's strategic significance escalated in the Second World War as Britain's maritime empire, and the shipping lanes that underpinned it, were challenged from both the east and the west.

While Singapore is famed as an imperial military base that failed, and Malta heralded as an imperial military base that held, Ceylon remains uncelebrated in general histories of the war. Yet its enormous strategic significance was recognized by leaders and commanders at the time: Stanley Bruce, Australia's High Commissioner in London and former prime minister, wrote that ‘the defence of Ceylon was a matter of importance, second only to that of the British Isles’. Winston Churchill described Ceylon as ‘that indispensable island’. In conversation at the British Embassy in Washington in 1946, the former prime minister said that:

the most dangerous moment of the war, and the one which caused me the greatest alarm, was when the Japanese fleet was heading for Ceylon and the naval base there [April 1942]. The capture of Ceylon, the consequent enemy control of the Indian Ocean, and the possibility at the same time of a German conquest of Egypt would have closed the ring and the future would have been black.