On September 28, 480, the Athenian navy destroyed the Persian invasion fleet in the Bay of Salamis. Had the Persians won, such noted figures as Plato, Aristotle, and Alexander along with democracy itself might have been erased from history. This original survey charts 50 such defining and revolutionary moments from the annals of history, concluding with September 11, 2001, and shows how the events of a single day can shape the future in a myriad of ways. Some of the events mark the end of an era while others paved the way for something new, and while many are bloody battles, others are momentous decisions or breathtaking discoveries. Together, they are remembered as powerful symbols of their time and pivotal moments in Western history.