was called in ancient times the Olympic
Straits, and a part of it formed a romantic and beautiful glen called
the Vale of Tempe. There was a road through this pass, which was the
only access by which Thessaly could be entered from the eastward.

To the south of the Vale of Tempe, the mountains, as will appear from
the map, crowded so hard upon the sea as not to allow any passage to the
eastward of them. The natural route of Xerxes, therefore, in descending
into Greece, would be to come down along the coast until he reached the
mouth of the Peneus, and then, following the river up through the Vale
of Tempe into Thessaly, to pass down toward the Peloponnesus on the
western side of Ossa and Pelion, and of the other mountains near the
sea. If he could get through the Olympic Straits and the Vale of Tempe,
the way would be open and unobstructed until he should reach the
southern frontier of Thessaly, where there was another narrow pass
leading from Thessaly into Greece. This last defile was close to the
sea, and was called the Straits of Thermopylae.

Thus Xerxes and his hosts, in continuing their march to the southward,
must necessarily traverse Thessaly, and in doing so they would have two
narrow and dangerous defiles to pass--one at Mount Olympus, to get into
the country, and the other at Thermopylae, to get out of it. It
consequently became a point of great importance to the Greeks to
determine at which of these two passes they should make their stand
against the torrent which was coming down upon them.

This question would, of course, depend very much upon the disposition of
Thessaly herself. The government of that country, understanding the
critical situation in which they were placed, had not waited for the
Athenians and Spartans to send embassadors to them, but, at a very early
period of the war--before, in fact, Xerxes had yet crossed the
Hellespont, had sent messengers to Athens to concert some plan of
action. These messengers were to say to the Athenians that the
government of Thessaly were expecting every day to receive a summons
from Xerxes, and that they must speedily decide what they were to do;
that they themselves were very unwilling to submit to him, but they
could not undertake to make a stand against his immense host alone; that
the southern Greeks might include Thessaly in their plan of defense, or
exclude it, just as they thought best. If they decided to include it,
then they must make a stand at the