a short history on Battle of
Thermopylae...
From Wikipedia
In the Battle of Thermopylae of 480 BC an alliance of Greek
city-states fought the invading Persian army in the pass of
Thermopylae. Vastly outnumbered, the Greeks delayed the enemy in
one of the most famous last stands of history. A small force led by
King Leonidas of Sparta blocked the only road through which the
massive army of Xerxes I could pass. The Persians succeeded in
defeating the Greeks but sustained heavy losses, disproportionate
to those of the Greeks. A local resident named Ephialtes betrayed
the Greeks, revealing a mountain path that led behind the Greek
lines. Dismissing the rest of the army, King Leonidas stayed behind
with 300 Spartans and 700 Thespian volunteers. Though they knew it
meant their own deaths, they secured the retreat of the other Greek
forces.
The losses of the Persian army alarmed Xerxes. When his navy was
later defeated at Salamis he fled Greece leaving only part of his
force to finish the conquest of Greece. It was defeated at the
Battle of Plataea.
The performance of the defenders at the battle of Thermopylae is
often used as an example of the advantages of training, equipment
and good use of terrain to maximise an army's potential, as well as
a symbol of courage against overwhelming odds. The heroic sacrifice
of the Spartans and the Thespians has captured the minds of many
throughout the ages and has given birth to many cultural references
as a result.