Here the great Pontic army and the fleet had completely mastered Bithynia, and compelled the Roman consul Cotta to take shelter with his far from numerous force and his ships within the walls and port of Chalcedon, where Mithradates kept them blockaded.
The Romans Defeated at Chalcedon This blockade, however, was so far a favourable event for the Romans, as, if Cotta detained the Pontic army before Chalcedon and Lucullus proceeded also thither, the whole Roman forces might unite at Chalcedon and compel the decision of arms there rather than in the distant and impassable region of Pontus.

Lucullus did take the route for Chalcedon; but Cotta, with the view of executing a great feat at his own hand before the arrival of his colleague, ordered his admiral Publius Rutilius Nudus to make a sally, which not only ended in a bloody defeat of the Romans, but also enabled the Pontic force to attack the harbour, to break the chain which closed it, and to burn all the Roman vessels of war which were there, nearly seventy in number.

On the news of these misfortunes reaching Lucullus at the river Sangarius, he accelerated his march to the great discontent of his soldiers, in whose opinion Cotta was of no moment, and who would far rather have plundered an undefended country than have taught their comrades to conquer.

His arrival made up in part for the misfortunes sustained: the king raised the siege of Chalcedon, but did not retreat to Pontus; he went southward into the old Roman province, where he spread his army along the Propontis and the Hellespont, occupied Lampsacus, and began to besiege the large and wealthy town of Cyzicus.
He thus entangled himself more and more deeply in the blind alley which he had chosen to enter, instead of--which alone promised success for him--bringing the wide distances into play against the Romans.
Mithradates Besieges Cyzicus In few places had the old Hellenic 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.