The Spartans (documentary) the Spartan constitution into the militarised state we know of today. Homosexuality among men and boys was mandatory. The training of Spartan youths is explained, from their enrollment in the Agoge system right through to their attainment of citizenship. The class structure of the Lacedaemonian state (Helots, Perioeci, and the soldier-citizens themselves) is also covered. The episode ends with the battle of Thermopylae, in which 300 Spartans, including their king, Leonidas, were killed in action defending Greece from a Persian invasion. Part 2 opens with the retreat of the Persians, after Thermopylae and the battle of Salamis. Athens, which had
Thermopylae shoreline has also advanced over the centuries because of the sedimentary deposition. The level of the Malian Gulf was also significantly higher during prehistoric times and the Spercheios River was significantly shorter. Its shoreline advanced by up to 2 kilometers between 2500 BC and 480 BC but still has left several extremely narrow passages between the sea and the mountains. The narrowest point on the plain, where the Battle of Thermopylae was probably fought, would have been less than wide. Between 480 BC and the 21st century, the shoreline advanced by as much as in places, eliminating the narrowest points