The 'brutalisation of warfare' - the employment by soldiers and armies of violence disproportionate to their military objectives in violation of international law - occurred widely and to varying degrees during the Second World War. Yet historians have been notably divided over its causes. One school of thought has located the source of atrocities in battlefield dynamics, while others have argued that racism and racist propaganda lay at the root of wartime barbarism. The Allied campaign in Burma and India - the object of this thesis - offers an opportunity to examine the development of brutal is at ion in a hitherto neglected context. The thesis first investigates general patterns of exceSSIve combat brutality during World War II, arguing that the images that armies held of the enemy largely determined his treatment, and that the development of enemy images was a theatre-of-war-specific process rather than one pre-determined by cultural stereotypes, as argued by John W. Dower and others. Next, an analysis of British troop morale illustrates the initial lack of motivation for fighting the Japanese, and shows how the British command's countermeasures helped shape the troops' view of the enemy. The thesis then considers the impact of Japanese military culture on the fighting, and argues that the Japanese military ethos and the resulting combat methods alone sufficed to foster ever-increasing brutality. A further element of analysis is the colonial context of the campaign, which made race a highly sensitive issue and limited the influence of white racism on the development of brutalisation. The final chapter turns to the American combat experience in the theatre and analyses the differences and parallels between British and American attitudes toward the campaign and the enemy. The thesis concludes that Japanese military conduct ultimately fuelled brutalisation by convincing Allied troops that retaliation - however unlawful - was morally and militarily justified.