In the Malayn campaign Australians managed to hold up the Japanese advance to great effect. The Australians lost over 2000 soldiers, either killed, missing or presumed dead. The situation at this stage was virtually hopeless. The various Allies failed to provide air cover, many of the British Indian soldiers were poorly motivated, and the whole affair which had the potential to become a military disaster, eventually did.
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On February 15th 1942, the British commander of the Allied forces in Southeast Asia, surrended to the Japanese unconditionally. In the sudden and unexpected silence of the surrender, the Australian troops had absolutely no idea of how they would be treated by the Japanese victors who disliked the Australians for their involvement in the ongoing war. The Australian soldiers soon learned and realised that they had to bow to their captors or run the risk of being bashed or even killed, so it seems that they were helpless in this situation at hand. The Japanese code demanded that a soldier commit suicide rather than having to endure the disgrace and torment of being held in captivity by the Japanese. The Allies however, had different viewpoints. Having fought to the best of their ability and being forced to surrender, the only option available to them was to wait and see what the next day would bring - while planning to escape or rebel, or keep hassling the Japanese to some extent if they possibly could.
Japanese officials suddenly found themselves in control over around one hundred thousand British, Indian, Dutch and Australian Troops who had to be fed and contained in a way that would allow them to survive. They did not want to divert large numbers of troops from their own army to look after the soldiers. Escape was essentially out of the question. So the Japanese decided to corral the troops on the Changi Peninsula of Singapore, cream off all the senior soldiers and take them away to Manchuria - but decided that they should leave the military structure intact so that the Allies would ultimately be responsible for organising themselves.