the persian empire attacked greece by both land and sea
In the spring of 492 BC an expeditionary force, to be commanded by Darius's son-in-law Mardonius, was assembled, consisting of a fleet and a land army. Whilst the ultimate aim was to punish Athens and Eretria, the expedition also aimed to subdue as many of the Greek cities as possible. Departing from Cilicia, Mardonius sent the army to march to the Hellespont, whilst he travelled with the fleet. He sailed round the coast of Asia Minor to Ionia, where he spent a short time abolishing the tyrannies that ruled the cities of Ionia. Ironically, since the establishment of democracies had been a key factor in the Ionian Revolt, he replaced the tyrannies with democracies.
First Persian invasion of Greece