At the beginning, it was the Phoenicians who abducted the daughter of the king of Argos. Then the Greeks paid them back by kidnapping Europa, the daughter of the king of Tyre, as well as Medea (although in her case she seems to have been a willing participant). The Trojans took Helen, hardly a cause for war according to the Persian viewpoint, but the Greeks held a grudge against the barbarians for centuries (their victory at Troy notwithstanding) and the Athenians helped the Ionians in their revolt against the great king Darius. He prevailed and commanded a servant to repeat to him, daily, at dinner time “"Lord, don't forget the Athenians.” Darrius did not and in 490 BCE he sent a mighty army to Marathon.