on not of a raid upon
Europe, but of an invasion in which the whole power of his vast empire was
to be put forth by sea and land.

It was fortunate for Greece that the man who then counted for most in the
politics of Athens was one who recognized the all-importance of sea-power,
though it is likely that at the outset all he had in mind was that the
possession of an efficient fleet would enable his city to exert its
influence on the islands and among the coast cities to the exclusion of the
military power of its rival Sparta. When it was proposed that the product
of the silver mines of Laurium should be distributed among the Athenian
citizens, it was Themistocles who persuaded his fellow-countrymen that a
better investment for the public wealth would be found in the building and
equipment of a fleet. He used as one of his arguments the probability that
the Persian King would, sooner or later, try to avenge the defeat of
Marathon. A no less effective argument was the necessity of protecting
their growing commerce. Athens looked upon the sea, and that sea at once
divided and united the scattered Greek communities who lived on the coasts
and islands of the Archipelago. It was the possession of the fleet thus
acquired that enabled Themistocles and Athens to play a decisive part in
the crisis of the struggle with Asia.

It was in the spring of B.C. 480 that the march from Asia Minor began. The
vast multitude gathered from every land in Western Asia, from the shores of
the Mediterranean to the Persian Gulf and the wild mountain plateaux of the
Indian border, was too numerous to be transported in any fleet that even
the Great King could assemble. For seven days and nights it poured across
the floating bridge that swayed with the current of the Dardanelles, a
bridge that was a wonder of early military engineering, and the making of
which would tax the resources of the best army of to-day. Then it marched
by the coast-line through what is now Roumelia and Thessaly. It ate up the
supplies of the lands through which it passed. If it was to escape famine
it must keep in touch with the ships that crossed and recrossed the narrow
seas, bringing heavy cargoes of food and forage from the ports of Asia, and
escorted by squadrons of long war galleys.

Every Greek city had been warned of the impending danger. Even those who
remembered Marathon, the day when a few thousand spearmen had routed an
Asiatic horde outnumbering them tenfold, rea