This means that 6,000 Greek Soldiers have fought over 100,000 Persian soldiers or even more, but sadly 300 elite Spartans stayed behind to defend the retreating army and to slow down the Persians. This matters because when the small Greek army defeated the Persian soldiers, which were over 100,000, they were known to be strong. This also sets an example that teamwork can change everything and the alliance Athens had made with the Greek city-states had helped all of them to prepare for the battle. After the war, the Persians left Greece and never wanted to fight again, which also makes Athens and Sparta the most powerful city-states in Greece. This is why the battle of Thermopylae was so important in the legacy of Ancient Greek history. A legacy of Ancient Greece that is most important is The Battle of Thermopylae. The battle of Thermopylae is the most important legacy because when the threat from the Persian emperor came to Athens they knew they had to be clever, so Athens forged a strong alliance with the other Greek city-states including Sparta, Sparta and Athens had been nemesis for many previous