threats into a unity much larger than its parts had the serious potential of overturning Roman power. The immediate cause of the Third War was the bequest to Rome by King Nicomedes IV of Bithynia of his kingdom upon his death (74 BC). Mithridates, who had been rebuilding his forces, launched an invasion of Bithynia. Forces and initial deployments, 74–73 BC Having launched an attack at the same time as a revolt by Sertorius swept through the Spanish provinces, Mithridates was initially virtually unopposed. The Senate responded by sending the consuls Lucius Licinius Lucullus and Marcus Aurelius Cotta to deal with the Pontic threat. The only other possible general for such an important command, Pompey, was in Hispania to help Metellus Pius crush the revolt led by Sertorius. Lucullus was sent to govern Cilicia and Cotta to Bithynia. According to Appian and Plutarch Lucullus had 30,000 infantry and 1,600–2,500 cavalry while Mithridates was rumoured to have as many as 300,000 men in his force. The original plan was that Cotta should tie down Mithridates' fleet, while Lucullus attacked by land. Cotta was therefore ordered to station his fleet at Chalcedon, while Lucullus marched through Phrygia with the intention of invading Pontus. Lucullus had not advanced far when news came through that Mithridates had made a rapid march westward, attacked and defeated Cotta at the Battle of Chalcedon, and forced him to flee behind the walls of Chalcedon. Sixty-four Roman ships had been captured or burnt, and Cotta had lost three thousand men. There Cotta was forced to remain until Lucullus could come to his rescue. Mithridates's defeat in western Asia, 73–72 BC Having made his way to Nicomedia, Cotta watched in frustration as Mithridates marched on taking Nicaea, Lampsacus, Nicomedia and Apameia, all major cities in the region. Only nearby Cyzicus held to the Roman cause, probably because many of its citizens (serving in Cotta's army as auxiliaries) had died fighting against Mithridates at Chalcedon. The Pontic army marched on Cyzicus and began a siege. Lucullus was camped somewhere along the Sangarius river in Bithynia when he received news of Cotta's defeat. His soldiers urged him to leave Cotta to his own folly and march on undefended Pontus with its rich potential for loot. Lucullus ignored them and headed toward Chalcedon. Marcus Marius, a Roman rebel cooperating with Mithridates, blocked and confronted him. They faced off at Otroea near Nicaea