Greek Wars > Greco-Persian Wars
The Greco-Persian Wars were a series of wars between Greece and Persia that represented a major clash of civilizations. From the Persian point of view, the conquest of the Greeks should have been another guaranteed victory for their empire building which spanned from the Indus Valley into Persia, Mesopotamia and Egypt along with Asia Minor. The first incursion into Asia Minor and the Greek civilization by the Persians occurred under Cyrus the Great in 547 BC. By the time of the Greco-Persian Wars many Greek city-states especially in Ionia had capitulated to Persian rule and were vassals in their satrapy empire.
However, in 499 BC the city-states of Athens and Eretria would help sponsor the Ionian Revolt which saw several city-states on Asia Minor rebel against Persian rule under Darius I the Great. In 490 BC as punishment for this act of insolence, the Persians launched a full scale invasion of Asia Minor and Greece which saw the complete destruction of Eretria. However, the fiercely independent city-states of Athens and Sparta were not to be conquered so easily.
The first major defining conflict of the Greco-Persian Wars was the Battle of Marathon where in 499 BC the Athenian hoplites under Militades defeated the more numerous Persians and forced them to flee back to their ships. Following this victory, a runner was sent to Athens named who managed to run the 26 miles and informed them of the outcome before dying from exhaustion. However, the Persian navy was still headed to Athens and the troops from Marathon managed to cover the same distance and met the Persians on the beach.
The war weary Persians were impressed by the hoplites standing on the shore ready to die for their city and they retreated. This marked the first major victory for the Greeks against the empire of Persia and was a huge propaganda boon that would continue to this day. It was said the Spartans arrived later at the battlefield to observe the carnage and were impressed by their Athenian counterparts who they routinely mocked.
Not to be outdone, the Persians under Xerxes I would invade Greece once again to avenge the outcome at Marathon and this time it would be the Spartans who rode out to meet them. After burning Athens to the ground in 480 BC the Spartans led by king Leonidas managed to hold off against a force of between 70,000 and 300,000 Persians. This engagement would become known as the Battle of Thermopylae for the small rocky pass where it occurred allowed the significantly outnumbered Spartans to hold off the Persian forces from invading mainland Greece for several days before being cut down due to the informing of a path to outflank the Spartans by a traitor.
While the Spartans would be defeated this emboldened all of Greece to rise up against the Persians and following the naval conflict at the Battle of Salamis under Thermistocles the Greeks soundly defeated the Persians which prevented them from gaining a foothold in Greece. In fact, if Greece had lost this battle it is likely that they would have been forced to become a vassal satrapy under the Persians and this would have greatly impacted the future development of western civilization.