Why did the Alfred Dreyfus affair capture the world's attention?

Alfred Dreyfus was an officer in the French Army when he was arrested 130 years ago for treason, convicted and sent to Devils Island for 5 years in solitary confinement.  His battle for justice divided the population of France and fascinated people across the globe.  How much of his persecution can be put down to antisemitism and why is this case still so relevant?

Guest: Maurice Samuels, author of Alfred Dreyfus: The man at the centre of the affair (Yale University Press)