Final answer:
The Battle of Thermopylae is considered a glorious defeat because the outnumbered Spartans showed extraordinary courage and resistance against the invading Persian army. Their stand led to unity among Greek city-states and ultimately, victory in the Battle of Salamis.
Step-by-step explanation:
The Battle of Thermopylae in 480 BCE is considered the most glorious defeat due to the extraordinary courage and spiteful resistance shown by the Greeks, especially the Spartans under King Leonidas, against a massively superior Persian army led by King Xerxes. Despite being massively outnumbered, the Spartan force was able to hold off the Persian army for three days, serving as a significant impediment to the Persian advance into Greece. Spartan soldiers, even upon knowing their inevitable death, chose to stand their ground to defend their homeland and their values, preferably dying as warriors rather than fleeing from the battlefield.
Their brave and fearless stand against the Persians inspired unity among the Greek city-states, ultimately resulting in a historic Greek victory at the Battle of Salamis. Even though the Spartans were defeated at Thermopylae, their sacrifice was not in vain. It served as a beacon of courage and selflessness inspiring their people to victory in the end thus making it one of history's most celebrated defeats.
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