Themistokles was the most significant leader in Athens during the 480/479 Persian invasion, as he was the main contributor to Greek victory. Despite the Greek success at Marathon, he prepared Athens for future threats from Persia.
Thucydides says that the Athenians built triremes "at the persuasion of Themistokles" to meet the possible threat of Darius and these were used to defeat the Persians at sea. Themistokles "turned them,[Athenians] to use Plato's phrase, from steadfast hoplites into sea-tossed mariners" as he realised the Persians were too strong on land. Themistokles also developed the port of Piraeus into a harbour so that they could ship supplies whilst fighting against the Persians.
As a direct result of Themistokles' urging, the Greeks were saved because of their naval strength, and the 180 Athenian ships contributed greatly to the Greek victory. Xerxes also fled because his ships were defeated, despite still having land forces- all due to Themistokles' plan of undermining Persian confidence by defeating them at sea.
While he was in power, Themistokles reconciled cities and leaders; and persuaded them to unite against the Persians. He forfeited his leadership to Eurybiades, while promising the Athenians that if they proved their fighting skills, the Greeks would accept their leadership. "For this action, Themistokles is generally regarded as the man most directly responsible for saving Greece, and also for earning for the Athenians the reputation of surpassing their enemies in courage and their allies in wisdom."
Themistokles pressed the Athenians to relinquish their city, as he knew it would be damaging for the Greeks to try and defend it. A marble slab was found in the Peloponnese ; which is a copy of a decree outlining the evacuation Themistokles instigated. This establishes that Themistokles was one of the main reasons for Greek victory-...