The enormous loss of life and physical destruction caused by the First World War led people to hope that there would never be another such catastrophe. How then did it come about that there was a Second World War causing twice the 30 million deaths and many times more destruction as had been caused in the previous conflict? The ‘Introduction’ poses several questions: why did this war start so soon after World War I? Why was it considered a world war and not just European? What triggered the involvement of various nations? How did the Allies win? These questions are considered in subsequent chapters.