Meanwhile community of interests between Mithridates and Tigranes had led to a complete reconciliation between them, and the Pontic king, who had spent a year and eight months in the dominions of his son-in-law without being admitted to a personal interview, was now made to participate in all the councils of Tigranes, and appointed to levy an army to unite in the war. But it was in vain that in the ensuing campaign (B.C. 69) he urged upon his son-in-law the lessons of his own experience, and advised him to shun a regular action with Lucullus: Tigranes, confident in the multitude of his forces, gave battle at Tigranocerta, and was defeated, before Mithridates had been able to join him. But this disaster, so precisely in accordance with the warnings of Mithridates, served to raise the latter so high in the estimation of Tigranes, that from this time forward the whole conduct of the war was intrusted to the direction of the King of Pontus. In the following summer (B.C. 68) Lucullus crossed the Taurus, penetrated into the heart of Armenia, and again defeated the allied monarchs near the city of Artaxata. But the early severity of the season, and the discontent of his own troops, checked the farther advance of the Roman general, who turned aside into Mesopotamia. Here Mithridates left him to lay siege to the fortress of Nisibis, which was supposed to be impregnable, while he himself took advantage of his absence to invade Pontus at the head of a large army, and endeavor to regain possession of his former dominions. The defense of Pontus was confided to Fabius, one of the lieutenants of Lucullus; but the oppression of the Romans had excited a general spirit of disaffection, and the people crowded around the standard of Mithridates. Fabius was totally defeated, and compelled to shut himself up in the fortress of Cabira. In the following spring (B.C. 67), Triarius, another of the Roman generals, was also defeated with immense loss. The blow was one of the severest which the Roman arms had sustained for a long period: 7000 of their troops fell, among whom were an unprecedented number of officers, and their camp itself was taken.