Armed conflict beginning in September 1939 with the invasion of Poland by Nazi Germany (although Japan had invaded China in 1937). It became a ‘world war’ in a truer sense in 1941 after the bombardment of Pearl Harbour by the Japanese and the consequent declaration of war by the US on Japan and Germany. Although in terms of the percentage of soldiers killed it was a less bloody war than the first world war, the total sum of the dead – approximately 40 million – was devastating. For the first time in history in a major war the civilian dead outnumbered those within the fighting forces. The war is also infamous for Nazi Germany’s medical experiments on human beings, and its sterilisation and so-called ‘euthanasia’ programmes.