On September 1st, 1939, Nazi Germany invaded Poland. Two days later, France and the United Kingdom declared war on the Third Reich. This was the beginning of what would become perhaps the most devastating clash in human history. By the end of the war, tens of millions of people had been killed, wounded or displaced, and the world order had been irrevocably altered. So how exactly did WW2 start?

In this episode, Dan explains how and why the Second World War came about. He examines both the immediate triggers and the big substructural forces that pushed humanity into a devastating conflict that continues to shape our world today.

Written and produced by Dan Snow, and edited by Dougal Patmore.

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