Please note that Mommsen uses the AUC chronology (Ab Urbe Condita), i.e. from the founding of the City of Rome. You can use this reference table to have the B.C. dates
From: The History of Rome, by Theodor Mommsen
Translated with the sanction of the author by William Purdie Dickson
When the war with Perseus broke out, the Rhodians, like all other sensible Greeks, viewed it with regret, and blamed Eumenes in particular as the instigator of it, so that his festal embassy was not even permitted to be present at the festival of Helios in Rhodes. But this did not prevent them from adhering to Rome and keeping the Macedonian party, which existed in Rhodes as well as everywhere else, aloof from the helm of affairs. The permission given to them in 585 to export grain from Sicily shows the continuance of the good understanding with Rome.
All of a sudden, shortly before the battle of Pydna, Rhodian envoys appeared at the Roman head-quarters and in the Roman senate, announcing that the Rhodians would no longer tolerate this war which was injurious to their Macedonian traffic and their revenue from port-dues, that they were disposed themselves to declare war against the party which should refuse to make peace, and that with this view they had already concluded an alliance with Crete and with the Asiatic cities.
Many caprices are possible in a republic governed by primary assemblies; but this insane intervention of a commercial city--which can only have been resolved on after the fall of the pass of Tempe was known at Rhodes--requires special explanation.
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Reference address : https://www.ellopos.net/elpenor/rome/3-10-third-macedonian-war.asp?pg=43