Athens
Explanation:
Athens defeated Persian forces decisively in the Battle of Marathon despite the numeric advantage of the Persians.
The Persians lost because of their bad strategic choices mostly, like ending most of their fleet around a tiny island and then getting stranded by the Athenian forces which ensued a battle on the shallow waters.
This battle ended the Persian efforts on Greece for a long time until Xerxes, the son of Darius went to fight the Greeks again.
