Thermopylae

Between 480 BC and the 21st century, the shoreline advanced by as much as 9 km (5.6 mi) in places, eliminating the narrowest points of the pass and considerably increasing the size of the plain around the outlet of the Spercheios.

[3] The A1 motorway linking Athens and Thessaloniki now follows the ancient shoreline and thus splits the pass; a modern-day monument to King Leonidas I of Sparta is situated on the east side of the highway, directly across the road from the hill where Simonides' epitaph to the fallen is engraved in stone at the top.

[5] The first known Amphictyony, a group of religiously associated ancient Greek tribes, was centered on the cult of Demeter at the city of Anthela, near Thermopylae.

The delegates to this first Amphictyony were dubbed the Pylagorai ("gate-assemblers"); since Demeter had chthonic or underworld associations in many of her older cults, this may be a reference to the gates of Hades.

[6] Thermopylae is primarily known for the battle that took place there in 480 BC, in which an outnumbered Greek force probably of 7,000[7] (including 300 Spartans, 500 warriors from Tegea, 500 from Mantinea, 120 from Arcadian Orchomenos, 1,000 from the rest of Arcadia, 200 from Phlius, 80 from Mycenae, 400 Corinthians, 400 Thebans, 1,000 Phocians, 700 Thespians, and the Opuntian Locrians) held off a substantially larger force of Persians[8] under Xerxes.

[9] Gaius Stern has argued that this force had already suffered casualties of over 100 in the previous fighting, so the true number might be closer to 1,250 than 1,400.

In 353 BC/352 BC during the Third Sacred War, fought mainly between the forces of the Delphic Amphictyonic League, principally represented by Thebes, and latterly by Philip II of Macedon, and the Phocians.

In 279 BC a Gallic army led by Brennus initially engaged the Aetolians who were forced to make a tactical retreat and who were finally routed by the Thessalians and Malians by the river Spercheios.

In 191 BC Antiochus III the Great of Syria attempted in vain to hold the pass against the Romans under Manius Acilius Glabrio.

At an uncertain date in the mid 3rd century AD, the Germanic tribe of Heruli were defeated by a Roman force sent to stop them.