They were major steps in persuading the Persian Empire to stop trying to impose peace in the Eastern Mediterranean.
The decade before the Battle of Marathon took place between 499 BCE and 490 BCE. The Battle of Marathon itself occurred in 490 BCE.
After the Persian navy had been defeated in 480 at Salamis, the Greek cities were able to concentrate and defeat the Persian army, ending the invasion of peninsular Greece.
Persia had a king, not an emperor. The Persian king Darius I was at home in Persia when the battle of Marathon took place, so he was not killed at Marathon. Darius the Great died of natural causes 14 years after Marathon.
Would you like to rewrite the question so that it is comprehensible.
26 miles was the distance the Greek runner covered, while running, to declare "Nike" after the last major sea battle during the Peloponnesian Wars. The Greeks begun honoring this distance as a 'marathon' distance.
They arranged the battle so as to split the Persian fleet, in narrow channels and attacked them from the flanks whilethey were still badly deployed for battle.
The name of the King that was fighting in the battle of the Marathon was Leonidas. I am not sure which King you are talking about, but this is Athens King.Reality:Leonidas was not present at Marathon since he is the king of Sparta and they(the spartan army) arrived late for the battle due to a festival. Athens was a democracy so it had no king. The only king that might have been present was the king of Plataea(the only greek city who helped athens) but history seem to have forgotten his name.Addendum:True, there were no kings at Marathon. Perhaps the first answerer is confusing it with the fight at Thermopylae ten years later, when the Spartan king Leonidas led the defence of the pass, or the battle of Plataea eleven years later when there were two kings present - Pausanias king of Sparta and Xerxes king of Persia.
The sea battle of Salamis defeated the Persian fleet which had to withdraw back to Asia Minor, leaving the Persian army unsupported and without its supply fleet, so half of the army had to go home. This left the reduced Persian army open to defeat at Plataia the following year and the invasion was defeated.
Superior strategy they split the Persian fleet so that a third of it was not present at the battle, so evening up the numbers of ships on either side. Superior tactics - they engaged the Persian fleet when it was strung out coming around an island in the middle of the strait st Salamis.
The Greek coalition opposing the Persian attempt to impose peace on them selected the Salamis strait as the place to defeat the Persian fleet after earlier failing at Artemesion. The Persians wished to reliminate the Greek fleet. So it was a mutually satisfctoy arrangement, and the battle was started.
Salamis (sea), Plataea (land) and Mycale (sea-land).
Marathon is a plain just north of Athens. It was the site of a battle where Athens and Plataea defeated a Persian expeditionary force.