Darius I was the Persian king whose forces were defeated at the Battle of Marathon in 490 BCE.
The battle occurred during Darius’s campaign against the Greek mainland. Persian forces landed on the plain of Marathon, northeast of Athens, after earlier operations in the Aegean. The Athenian army, supported by Plataea, attacked the Persian position and won a major victory according to Herodotus.
Marathon did not end the Achaemenid Empire or permanently stop Persian influence in the Aegean. Darius continued preparing another expedition, but he died in 486 BCE before it could take place. His son Xerxes later launched the larger invasion of 480 BCE.
The famous story of a messenger running from Marathon to Athens is associated with later tradition and is not the same as the detailed ancient account of the battle. Herodotus instead describes Pheidippides’s earlier run from Athens to Sparta before the fighting.