The Rhodians endeavoured to make up for the time they had lost, and the money they had expended, during their war with Antiochus, by applying themselves entirely to navigation and commerce; so that, according to Polybius, they became masters of the sea, and the most opulent and flourishing state of those times.  The next war in which they were engaged was occasioned entirely by their attention and regard to their commercial interests.  We have already slightly noticed this war; but in this place it will be proper to go more into detail respecting it.  The people of Byzantium determined to lay a toll on all ships that traded to the Euxine, in order to defray an annual tribute which they were obliged to pay to the Greeks.  As one of the most important and lucrative branches of the commerce of Rhodes was to the countries lying on this sea, they were much aggrieved by this toll, and endeavoured to persuade the Byzantines to take it off, but in vain.  Under these circumstances, they, in conjunction with Prusias, king of Bythinia, declared war against the Byzantines; and while their ally took Hieron, which seems to have been a great mart of the Byzantines, and the resort of most of the merchants trading to these parts, the Rhodians, with a powerful fleet, ravaged their coasts, and seized all their ships trading to the Euxine.  The war was at length terminated under the mediation of the king of the Thracian Gauls; the Byzantines agreeing to take off the toll.

Their success in this war was counterbalanced by a dreadful earthquake, which threw down the Colossus, destroyed the arsenal, and damaged part of the walls and city.  As the Rhodians, however, were much esteemed by most of their neighbours, who found their prosperity intimately connected with the prosperity of Rhodes, they soon recovered from these calamities and losses.  Hiero, king of Syracuse, gave them 100 talents, and exempted them from all duties and taxes.  Ptolemy gave them also the like sum, besides one million measures of wheat, and timber, etc. requisite for building fifty ships.  Antiochus exempted all their vessels, which traded to his ports, from every kind of tax and duty.  They received from other princes presents or privileges of equal importance and value; so that, in a very short time, they recovered their former opulence and trade, and rebuilt their walls, etc.

Their alliance with Attalus, king of Pergamus, involved them in a war with Philip king of Macedonia, and was the cause of their forming an alliance with the Romans.  In this war the Rhodian fleet, in conjunction with the fleets of their allies, gained several victories over the fleet of Philip.  The latter was at length obliged to sue to the Romans for peace, and they, in fixing the terms, included the Rhodians, to whom were ceded Stratonice, and the greater part of Caria.  In the meantime Antiochus and the Romans had commenced hostilities, and the Rhodians were again involved in them:  almost at their very commencement, their fleet was surprized by a stratagem of Antiochus’s admiral, and of thirty ships of war of which it consisted, only seven escaped.