This prince followed at first his father's example, and abstained from mixing himself up in the Mithridatic war; but in B.C.
66, being courted by both sides, and promised the restoration of the provinces lost to Tigranes, he made alliance with Pompey, and undertook, while the latter pressed the war against Mithridates, to find occupation for the Armenian monarch in his own land.

This engagement he executed with fidelity.

It had happened that the eldest living son of Tigranes, a prince bearing the same name as his father, having raised a rebellion in Armenia and been defeated, had taken refuge in Parthia with Phraates.
Phraates determined to take advantage of this circumstance.

The young Tigranes was supported by a party among his countrymen who wished to see a youthful monarch upon the throne; and Phraates therefore considered that he would best discharge his obligations to the Romans by fomenting this family quarrel, and lending a moderate support to the younger Tigranes against his father.

He marched an army into Armenia in the interest of the young prince, overran the open country, and advanced on Artaxata, the capital.