Lastly, the most independent position among the intermediate states was held by the free Greek mercantile cities on the European shore of the Propontis as well as along the whole coast of Asia Minor, and on the islands of the Aegean Sea; they formed, at the same time, the brightest elements in the confused and multifarious picture which was presented by the Hellenic state-system. Three of them, in particular, had after Alexander's death again enjoyed their full freedom, and by the activity of their maritime commerce had attained to respectable political power and even to considerable territorial possessions; namely, Byzantium the mistress of the Bosporus, rendered wealthy and powerful by the transit dues which she levied and by the important corn trade carried on with the Black Sea; Cyzicus on the Asiatic side of the Propontis, the daughter and heiress of Miletus, maintaining the closest relations with the court of Pergamus; and lastly and above all, Rhodes. The Rhodians, who immediately after the death of Alexander had expelled the Macedonian garrison had, by their favourable position for commerce and navigation, secured the carrying trade of all the eastern Mediterranean; and their well-handled fleet, as well as the tried courage of the citizens in the famous siege of 450, enabled them in that age of promiscuous and ceaseless hostilities to become the prudent and energetic representatives and, when occasion required, champions of a neutral commercial policy. They compelled the Byzantines, for instance, by force of arms to concede to the vessels of Rhodes exemption from dues in the Bosporus; and they did not permit the dynast of Pergamus to close the Black Sea. On the other hand they kept themselves, as far as possible, aloof from land warfare, although they had acquired no inconsiderable possessions on the opposite coast of Caria; where war could not be avoided, they carried it on by means of mercenaries. With their neighbours on all sides they were in friendly relations--with Syracuse, Macedonia, Syria, but more especially with Egypt--and they enjoyed high consideration at these courts, so that their mediation was not unfrequently invoked in the wars of the great states. But they interested themselves quite specially on behalf of the Greek maritime cities, which were so numerously spread along the coasts of the kingdoms of Pontus, Bithynia, and Pergamus, as well as on the coasts and islands of Asia Minor that had been wrested by Egypt from the Seleucidae; such as Sinope, Heraclea Pontica, Cius, Lampsacus, Abydos, Mitylene, Chios, Smyrna, Samos, Halicarnassus and various others. All these were in substance free and had nothing to do with the lords of the soil except to ask for the confirmation of their privileges and, at most, to pay a moderate tribute: such encroachments, as from time to time were threatened by the dynasts, were skilfully warded off sometimes by cringing, sometimes by strong measures. In this case the