fought with the Japanese in the Burma campaign. Churchill called it the worst disaster in British military history. The sinking of Prince of Wales and Repulse soon after the Japanese landings on Malaya, the fall of Singapore and other defeats in 1942, severely undermined British prestige, which contributed to the end of British colonial rule in the region after the war. Background Outbreak of war In the interwar years, Britain had established a naval base in Singapore after the Anglo-Japanese alliance had lapsed in 1923. As part of the Singapore strategy, the base formed a key part of British interwar defence planning for the region. Financial constraints had hampered construction efforts during the intervening period and shifting strategic circumstances had largely undermined the key premises behind the strategy by the time war had broken out in the Pacific. During 1940 and 1941, the Allies imposed a trade embargo on Japan in response to its campaigns in China and its occupation of French Indochina. The basic plan for taking Singapore was worked out in July 1940. Intelligence gained in late 1940–early 1941 did not alter that plan but confirmed it in the minds of Japanese decision makers. On 11 November 1940, the German raider Atlantis captured the British steamer Automedon in the Indian Ocean, carrying papers meant for Air Marshal Sir Robert Brooke-Popham, the British commander in the Far East. The papers included information about the weakness of the Singapore base. In December 1940, the Germans handed over copies of the papers to the Japanese. The Japanese had broken the British Army's codes and in January 1941, the Second Department (the intelligence-gathering arm) of the Imperial Army interpreted and read a message from Singapore to London complaining in much detail about the weak state of "Fortress Singapore", a message so frank in its admission of weakness that the Japanese at first suspected it was a British plant, believing that no officer would be so open in admitting weaknesses to his superiors. Only after cross-checking the message with the Automedon papers did the Japanese accept it to be genuine. Japanese oil reserves were rapidly depleting due to its military operations in China and by industrial consumption. In the latter half of 1941, the Japanese began preparing to go to war to seize vital resources if peaceful efforts to buy them failed. Planners determined a broad scheme of manoeuvres that incorporated simultaneous attacks