2,499 years ago the Persian 'Great King' Xerxes launched history's largest amphibious invasion of Europe before D-Day. Accompanied by a huge army and navy he crossed the Hellespont (modern day Dardanelles), intent on punishing the city-state of Athens and any other Hellenic powers that dared to resist. It was during this campaign that one of history's most famous battles was fought, at the Pass of Thermopylae in central Greece. King Leonidas, his 300 (or so) Spartans and their Hellenic allies fought off against King Xerxes' mighty Persian army for three days. To talk through this fascinating battle I'm chatting with Paul Cartledge, a professor from the University of Cambridge and one of the World's leading experts on ancient Sparta. In this fascinating chat, Paul sorts the fact from the fiction about the doomed Thermopylae defence. He starts by explaining the conflict's background, before moving on to the battle itself. We finish off by discussing how this famous battle ultimately created what we now know as 'the Spartan mirage'.

This episode will be the first in a small series dedicated to talking about the 480 BC clashes of the Second Persian War, for the 2,499th anniversaries of these battles. Paul is the author of 'Thermopylae: The Battle That Changed the World.'