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 Besieges Cyzicus
In few places had the old Greek adroitness and aptitude preserved themselves so pure as in Cyzicus; its citizens, although they had suffered great loss of ships and men in the unfortunate double battle of Chalcedon, made the most resolute resistance. Cyzicus lay on an island directly opposite the mainland and connected with it by a bridge. The besiegers possessed themselves not only of the line of heights on the mainland terminating at the bridge and of the suburb situated there, but also of the celebrated Dindymene heights on the island itself; and alike on the mainland and on the island the Greek engineers put forth all their art to pave the way for an assault.
But the breach which they at length made was closed again during the night by the besieged, and the exertions of the royal army remained as fruitless as did the barbarous threat of the king to put to death the captured Cyzicenes before the walls, if the citizens still refused to surrender. The Cyzicenes continued the defence with courage and success; they fell little short of capturing the king himself in the course of the siege.
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Reference address : https://www.ellopos.net/elpenor/rome/5-02-rule-sullan-restoration.asp?pg=30