Why was World War 2 a terrible war?

'We are by kin of the clan of Geats and Hygelac's own hearth-fellows we' IV 3 4? How did the complex web of European alliances contribute to the out break of world war 1? What was the round table and what did it signify? What three events shaped the views of Saint-Simon? What did the scientific revolution emphasize? What explorer was nicknamed Iberia's pilot? How did the post - World War 2 red scare compare and contrast with the one that followed world war 2? Was early modern period significant? What are the four social classes that emerged from aryan society? What countries were created as a result of ww1? How much was a French franc worth in 1815? What was the purpose of the human rights movements in the 19th and 20th centuries? What name was the war given in europe? Why Should people remember the french revolution? Who are the top good and bad leaders in history? What happened to the monarchy during 1553? How many abortions has world performed? Why was the slave trade called Triangular trade? The term feudalism is best defined as? Who was not one of the Allied nations during World War 1?

Why was World War 2 a terrible war?