History of the Peloponnesian War

They therefore first consulted the god at Delphi, and at his bidding sent out the colonists, consisting of both Spartans and Perioeci,[*](The old inhabitants, chiefly of Achaean stock, who had been reduced to a condition of dependence (not slavery) by the Dorians.) and they invited any other Hellenes who so desired to accompany them, except Ionians and Achaeans and certain other races. The founders of the colony in charge of the expedition were three Lacedaemonians, Leon, Alcidas, and Damagon.

When they had established themselves they built a new wall about the city, which is now called Heracleia, and is about forty stadia distant from Thermopylae and twenty from the sea. They then proceeded to build dockyards, and in order that the place might be easy to guard fenced off the approach on the side toward Thermopylae by a wall across the pass itself.