Meanwhile, however, the balance of advantage rested with the invaders.  The key of Northern Greece was won, and Phocis, Locris, Boeotia, Attica, and the Megarid lay open to the Persian army.  The Greek fleet could gain nothing by any longer maintaining the position of Artemisium, and fell back towards the south, while its leaders anxiously considered where it should next take up its station.  The Persians pressed on both by land and sea.  A rapid march through Phocis and Boeotia brought Xerxes to Athens, soon after the Athenians, knowing that resistance would be vain, had evacuated it.  The Acropolis, defended by a few fanatics, was taken and burnt.  One object of the expedition was thus accomplished.  Athens lay in ruins; and the whole of Attica was occupied by the conqueror.  The Persian fleet, too, finding the channel of the Euripus clear, sailed down it, and rounding Sunium, came to anchor in the bay of Phalerum.

In the councils of the Greeks all was doubt and irresolution.  The army, which ought to have mustered in full force at Thermopylae and Callidromus, and which, after those passes were forced, might have defended Cithseron and Parnes, had never ventured beyond the Isthmus of Corinth, and was there engaged in building a wall across the neck of land from sea to sea.  The fleet lay off Salamis, where it was detained by the entreaties of the Athenians, who had placed in that island the greater part of the non-combatant population; but the inclination was strong on the part of many to withdraw westward and fight the next battle, if a battle must be fought, in the vicinity of the land force, which would be a protection in case of defeat.  Could Xerxes have had patience for a few days, the combined fleet would have broken up.  The Peloponnesian contingents would have withdrawn to the isthmus; and the Athenians, despairing of success, would probably have sailed away to Italy.  But the Great King, when he saw the vast disproportion between his own fleet and that of the enemy, could not believe in the possibility of the Greeks offering a successful resistance.  Like a modern emperor, who imagined that, if only he could have been with his fleet, all would necessarily have gone well, Xerxes supposed that by having the sea-fight under his own eye he would be sure of victory.  Thus again, as at Artemisium, the only fear felt was lest the Greeks should fly, and in that way escape chastisement.  Orders were therefore issued to the Persian fleet to close up at once, and blockade the eastern end of the Salaminian strait, while a detachment repeated the attempted manoeuvre at Euboea, and sailed round the island to guard the channel at its western outlet.