The long peace of the past eight decades has rested on two revolutionary convictions: that wars of aggression are intolerable and that empires must end. The first principle emerged from the carnage of two world wars, which together killed a hundred million people. The second came from centuries of colonial subjugation and the fight across Asia, Africa, and Latin America for self-determination. The United Nations Charter, signed in San Francisco in June 1945, gave both convictions political form.