Here he was joined, not only by a number of the Parthian nobles, but also by the reigning king of Osrhoene, who bore the usual name of Abgarus.

The Parthians were anxious that he should advance at his best speed and by the shortest route on Ctesiphon, and the Roman governor, Cassius, strongly advised the same course; but Meherdates fell under the influence of the Osrhoene monarch, who is thought by Tacitus to have been a false friend, and to have determined from the first to do his best for Gotarzes.

Abgarus induced Meherdates to proceed from Zeugma to his own capital, Edessa, and there detained him for several days by means of a series of festivities.

He then persuaded him, though the winter was approaching, to enter Armenia, and to proceed against his antagonist by the circuitous route of the Upper Tigris, instead of the more direct one through Mesopotamia.

In this way much valuable time was lost.