(expanded a little from an email)
This year is the 2500th anniversary of the twin battles of Thermopylae and Salamis. The first Persian invasion of Europe ended at Marathon. After several years of preparation, Darius' son Xerxes tried again with an army that some historians have claimed had more than a million soldiers. That number is absurd, but it is telling that the Persians never needed 10 years to prepare for any of their other conquests.
Thermopylae was a classic pass defense and the defenders held until the attackers got around them to attack from both ends of the pass. Eventually, the Persians crushed the defenders and moved through the pass into Greece.
If that was the end of the story, no one today would know about Thermopylae. The men who died showing the biggest empire in the world how much it would cost to add Greece to that empire would be forgotten, because imperial rulers don't care about peon casualties, and there would have been no Greek cities to write about theirs.
Xerxes went about systematically destroying Greek cities that had defied him. One month later, however, the complete loss of his fleet at Salamis ended any chance of resupply or reinforcements.
Xerxes took a look at the map, compared his casualties against the Greek casualties, thought about losing more than 20,000 of his personal guard, the "Immortals", who were his best soldiers just to take a single stupid mountain pass and only getting less than a thousand of the defenders in return, thought about how many more mountain passes there were all over Greece, thought about all the rebellions all over his empire that would only get worse the longer he stayed stuck in the quicksand, and grabbed half of his remaining army and went home.
The half that stayed in Greece was wiped out during the winter. The Greeks ensured that they kept naval superiority to prevent another Persian invasion, and went back to squabbling among themselves. No Asian army ever crossed the Dardanelles again until the Turks finally took Constantinople in the 1400s and started thinking about Europe. They took Greece and held it for four hundred years, but they couldn't get much further into Europe. Greece's children felt the same way about empires.
As I'm sure all of you read about in my masterpiece "...In The Shade", the Greek survival of Persia's massive second invasion meant that, for the rest of the world's history, the Eurasian land mass has been divided between Western Civilization, with small nations which counted people as more important than the government, and Eastern Civilization, with huge empires which counted the government as more important than the people.
If you value your freedom, if you value even just the CONCEPT of individual freedom embedded at the heart of Western Civilization, thank the Spartans at Thermopylae and the Athenians at Salamis.
-ZM