This describes the origins, the methods and the result of imperial Japan's occupation of Southeast Asia during World War II. Japanese policy makers had recognized that the region's European colonial regimes would not last for ever, but they had not envisaged a military conquest. While Japan launched stunningly successful military operations - such as the attacks on Pearl Harbor and Singapore - it found devising occupation policies that were suitable to the diverse regions under its sway after 1941 much harder. To a large extent Japan's policies were improvised, often being based on models derived from the experiences of Manchuria or the homeland itself. For some Japanese the invasion was a work of "liberation", and those who tried to extricate Japan from the war as defeat loomed emphasized this rationale. Eventually, however, the people of the region "liberated" themselves, taking advantage of the interregnum between Japanese military defeat and the imposition of alternative Allied administrations. Any sense of obligation to the Japanese was reduced by the violence of their soldiery and the inadequacy of their administration.