The Defence And Fall Of Singapore 1940-1942, by Brian P. Farrell
Although Farrell presents his case very well, it gets repetitive and would have been better if shorter. But the narrative is shocking. At almost all levels, the British empire proved incapable of living up to the expectations it fostered in the Interbellum.
The British Empire based it's Far Eastern and Pacific strategy in the Interbellum on the defense of Singapore, but never committed the resources to put the plans into practice. The target of moving over a major battle fleet within a short span of time also quickly became an empty promise. The Empire's elite knew this but didn't dare reveal, because that would have lost them the trust and support of the colonies and especially Australia.
Then when war breaks out, it becomes even harder to build up in East Asia. Troops even get withdrawn to the Mediterranean Theatre, with Indian and Australian contingents following. There is a slow strengthening of defenses in the Far East as Japanese attack becomes imminent. Troops are shuttled back, but planning is poor. The airforce bases are built too far forward, which in turn spreads the ground forces too thin. There is even an idiotic plan for a spoiling attack into Thailand, which puts the troops on the wrong foot. And when the Japanese attack the scheme is abandoned.
Fleet Force Z (Prince of Wales and Repulse) arrives just in time, but is nothing like a major battle fleet. It's immediate loss is futile, while air cover (which was the reason for forward positioning of air bases and accompanying infantry) is bungled.
British forward forces are pressed back by Japanese aggressive attacks. The Japanese are weaker in numbers, but take the calculated risk of keeping up the pressure. British units gradually unravel. The defensive lines nearer Singapore are also broken through, mostly because no there's no strategic guidance and cooperation between divisions.
The Empire troops retreat in confusion to the island of Singapore, where reinforcements have arrived. Imperial forces still outnumbers the Japanese, but there still is no higher level co-ordination and the distrust between senior command and (Australian) sub commanders reaches bottom level. So when Japanese attack, there is no effective answer to a local breakthrough and Japanese achieve a remarkable victory.
The British lost the conflict on all levels: political, strategical and tactical. The politicians made promises they knew they could not keep (nothing new there), but even then the collapse of the defense was much worse than necessary. Empire forces were defeated by lack of coherent strategy resulting in dispersal of forces, lack of higher level co-ordination, mutual distrust, insufficient training in local circumstances, low quality of training for modern war in general.
Japanese succeeded despite being a smaller force working along tenuous supply lines. They made the right decisions about the nature of warfare in Malaya, despite not having previous experience in jungle terrain (contrary to the myth of Japanese being natural jungle fighters), and about keeping pressure on British forces. Also the troops and leadership had battle experience and good morale. This meant they were better able to deal with battlefield fluctuations than their untried and amateur opponents.
The loss of Singapore shattered the illusion that Great Britain could effectively defend its East Asian Empire, which meant that from then on the dominions looked to U.S. for help and the nationalist movements worked towards independence.