The French Revolution

A decade of radical political and social transformation in France between 1789 and 1799 that dismantled the monarchy, executed a king, and introduced the modern concepts of liberty, popular sovereignty, and secular governance to European politics. The Revolution produced the Declaration of the Rights of Man, the Reign of Terror, and eventually Napoleon Bonaparte. Its ideological exports -- nationalism, republicanism, the left-right political spectrum -- structured global politics for the next two centuries. It remains the single most studied political upheaval in Western history and a reference point for every subsequent revolution.

Added by @ethanwalsh