the persian empire attacked greece by both land and sea
First Persian invasion of Greece 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.[39] Whilst the ultimate aim was to punish Athens and Eretria, the expedition also aimed to subdue as many of the Greek cities as possible.[39][40] Departing from Cilicia, Mardonius sent the army to march to the Hellespont, whilst he travelled with the fleet.[39] 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.[39]