Around this time 2,499 years ago the famous Battle of Thermopylae was raging. But it is important to remember that this clash was not happening on its own. At the same time, to the east of Leonidas' defence, another battle was underway at sea between Xerxes' great armada and a much smaller Hellenic fleet plagued with internal problems. This was the Battle of Artemisium, an often-overlooked and overshadowed military encounter of the Persian Wars. Its importance, however, was sizeable. I was delighted to have Dr Owen Rees back on the show to talk through this clash, explaining its significance and how it paved the way for one of the most famous naval battles in history: Salamis. Owen is the author of 'Great Naval Battles of the Ancient Greek World.' This episode is the second in a small series covering 4 key clashes of 480 BC, the 2,499th anniversaries of which we are celebrating this year. Some mildly-strong language.