I should also note that today is one of the "accepted" dates for the Battle of Marathon in 490 BC. The Spartans were late to join the battle on account of a festival, and since the date of the festival is known in their lunisolar calendar (and we can calculate moon phases across a great stretch of time), a 19th century scholar worked out that same day in the Julian calendar.
The Athenian victory at Marathon had several important consequences;
- It proved that Athens could hold its own as a military power without Spartan aid.
- It proved that the Greek civilization could drive Persia out of Greek territory.
- In light of the above, the Battle of Marathon set the stage for the birth of the Classical period in Athens, which afterward began to draw the luminaries of Greece to itself, including Aeschylus, Sophocles, Euripides, Herodotus, Thucydides, Hippocrates, Plato and Socrates. This period culminated in the Age of Pericles, and came to an end with the fallout of the Pelopponesian War.