By way of recompense, Philip helped him to subdue the Greek mercantile cities in his territory.

Chalcedon submitted.
Cius, which resisted, was taken by storm and levelled with the ground, and its inhabitants were reduced to slavery--a meaningless barbarity, which annoyed Prusias himself who wished to get possession of the town uninjured, and which excited profound indignation throughout the Hellenic world.

The Aetolians, whose -strategus- had commanded in Cius, and the Rhodians, whose attempts at mediation had been contemptuously and craftily frustrated by the king, were especially offended.
The Rhodian Hansa and Pergamus Oppose Philip But even had this not been so, the interests of all Greek commercial cities were at stake.

They could not possibly allow the mild and almost purely nominal Egyptian rule to be supplanted by the Macedonian despotism, with which urban self-government and freedom of commercial intercourse were not at all compatible; and the fearful treatment of the Cians showed that the matter at stake was not the right of confirming the charters of the towns, but the life or death of one and all.

Lampsacus had already fallen, and Thasos had been treated like Cius; no time was to be lost.