Having brought all of Hellenic Asia Minor into revolt, Aristagoras evidently realised that the Greeks would need other allies in order to fight the Persians. In the winter of 499 BC, he sailed to mainland Greece to try to recruit allies. He failed to persuade the Spartans, but the cities of Athens and Eretria agreed to support the rebellion. In the spring of 498 BC, an Athenian force of twenty triremes, accompanied by five from Eretria, for a total of twenty-five triremes, set sail for Ionia. They joined up with the main Ionian force near Ephesus.