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
Mithradates, carried away by his successes, had formed the bold resolution that he would, like Antiochus, bring the war for the sovereignty of Asia to a decision in Greece, and had by land and sea directed thither the flower of his troops. His son Ariarathes penetrated from Thrace into the weakly-defended Macedonia, subduing the country as he advanced and parcelling it into Pontic satrapies. Abdera and Philippi became the principal bases for the operations of the Pontic arms in Europe. The Pontic fleet, commanded by Mithradates' best general Archelaus, appeared in the Aegean Sea, where scarce a Roman sail was to be found.
Delos, the emporium of the Roman commerce in those waters, was occupied and nearly 20,000 men, mostly Italians, were massacred there; Euboea suffered a similar fate; all the islands to the east of the Malean promontory were soon in the hands of the enemy; they might proceed to attack the mainland itself. The assault, no doubt, which the Pontic fleet made from Euboea on the important Demetrias, was repelled by Bruttius Sura, the brave lieutenant of the governor of Macedonia, with his handful of troops and a few vessels hurriedly collected, and he even occupied the island of Sciathus; but he could not prevent the enemy from establishing himself in Greece proper.
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Reference address : https://www.ellopos.net/elpenor/rome/4-08-east-king-mithradates.asp?pg=46