Victory at Thermopylae meant that all Boeotia fell to Xerxes; Attica was then open to invasion. The remaining population of Athens was evacuated, with the aid of the Allied fleet, to Salamis. The Peloponnesian Allies began to prepare a defensive line across the Isthmus of Corinth, building a wall, and demolishing the road from Megara, abandoning Athens to the Persians. Athens thus fell to the Persians; the small number of Athenians who had barricaded themselves on the Acropolis were eventually defeated, and Xerxes then ordered the destruction of Athens.