In a sense every event, however minor, changes the world in some way. Even the smallest occurrence can alter the course of time, and a sequence of small events, like those that triggered World War I, can change it dramatically. As Lenin said, everything is connected to everything else. All events are a mixture of cause and effect. Some historical events are very obvious candidates for inclusion in this book, like the Exodus or the Battle of Waterloo. Some major events seem powerful and momentous at the time, though we can see, perhaps many years afterwards, that their effects were not as far-reaching as we may once have imagined. Conversely other events were not seen as significant at the time, but they became so afterwards, like Abraham Lincoln's Gettysburg Address or the first aeroplane flight by the Wright Brothers. This books includes both positive and negative events, the only criterion is that they all altered the passage of human life forever. Those events that inspired hope or saved lives have been placed side-by-side with those that have killed and maimed or oppressed thousands. The result is a dynamic book crammed full of action, teamed with meticulous analysis and reflection.