y the possession of Macedonia, brought
his frontier into contact with Northern Greece. The overland route, in
any case the more satisfactory of the two, was now in the hands of the
invader.

Revolutions at Athens prevented him from setting out on his expedition
as soon as he had anticipated. Hippias had been overthrown in 510, and
having taken refuge at Sigoum, was seeking on all sides for some one
to avenge him against his fellow-citizens. The satrap of Sardes,
Arta-phernes, declined at first to listen to him, for he hoped that the
Athenians themselves would appeal to him, without his being obliged to
have recourse to their former tyrant. As a matter of fact, they sent him
an embassy, and begged his help against the Spartans. He promised it
on condition that they would yield the traditional homage of earth and
water, and their delegates complied with his demand, though on their
return to Athens they were disowned by the citizens (508). Artaphernes,
disappointed in this direction, now entered into communications with
Hippias, and such close relations soon existed between the two that
the Athenians showed signs of uneasiness. Two years later they again
despatched fresh deputies to Sardes to beg the satrap not to espouse
the cause of their former ruler. For a reply the satrap summoned them
to recall the exiles, and, on their refusing (506),* their city became
thenceforward the ostensible objective of the Persian army and fleet.
The partisans of Hippias within the town were both numerous and active;
it was expected that they would rise and hand over the city as soon as
their chief should land on a point of territory with a force sufficient
to intimidate the opposing faction. Athens in the hands of Hippias,
would mean Athens in the hands of the Persians, and Greece accessible to
the Persian hordes at all times by the shortest route. Darius therefore
prepared to make the attempt, and in order to guard against any mishap,
he caused all the countries that he was about to attack to be explored
beforehand. Spies attached to his service were sent to scour the coasts
of the Peloponnesus and take note of all its features, the state of
its ports, the position of the islands and the fortresses; and they
penetrated as far as Italy, if we may believe the story subsequently
told to Herodotus.**

* Herodotus fixes the date at the time when the Athenians
first ostracised the principal partisans of the
Pisistratids, and am