The fall of Croesus, in 547 B.C., marked the beginning of the absorption of the Ionian Greeks into the Persian empire. Half a century later, starting in 499, these Greeks began a succession of open rebellions against their Persian overlords; it was this “Ionian Revolt” that triggered what we now call the Persian Wars, the Asian invasions of the Greek mainland in 490 and 480. Some of the rebellious cities had appealed to Athens and Sparta for military aid, and Athens, at least, had responded. Herodotus tells us that the Great King Darius was so infuriated by this that he instructed a servant to repeat to him the injunction “Master, remember the Athenians!” three times whenever he sat down to dinner. Contemporary historians see a different, less personal motive at the root of the war that was to follow: the inevitable, centrifugal logic of imperialist expansion.