Marcus Aurelius Cotta, the Roman governor of Bithynia, was building up his forces when Mithridates invaded. Cotta, not ready to face Mithridates, retreated to
Chalcedon, where he had the fleet to his back, and sent urgent messages to former
consular colleague Lucullus, who had secured the command against Mithridates as his proconsular mission. Lucullus was in Asia, training and preparing his army to invade Pontus from the south, but he put his plans on halt and marched towards Bithynia to deal with the invasion. Unfortunately for the Romans, Cotta was drawn into a battle before the walls of Chalcedon and lost 3,000 men. Mithridates followed up this success with a combined land and sea assault in which he captured most of Cotta's fleet. Mithridates left Cotta under siege and marched his main army westward taking city after city until he reached the Roman-allied city of Cyzicus. ==Siege==