In evaluating what happened at Thermopylae and any other land battle in the Greek-Persian War it's always worth remembering that a Greek hopolite was better armed and armored than a Persian warrior, Their heads, bodies, and lower legs were well protected by bronze armor, they carrled a large round shield, and their basic weapon, the spea,r was longer and stronger than the Persian weapon.
They were wel trained in fighting in a close eight man deep formation which was called the phalanx. The name derives from the classic word for a roller of the type used to smooth and flatten roads and meant that the phalanx rolled over the enemy formation. Their superior weapons, armor and training explains why the Greeks won even when they were heaviky otnumbered.
THe Greeks held off the Persians attacks until a path around their position at Thermopylae through the mountains was betrayed to the Persians by a Greek traitor. Attacked by superior numbers from all sides the Greeks lost and died fighting to the last man. If it had not been for this traitor the Greeks could have held on much longr, perhaps long enough for reinforcements to have reached them from the south.
[This message has been edited by Hard Ball (edited October 29, 2000).]