These amicable relations between the two sovereigns would probably have continued undisturbed till the death of one or the other, had not a revolution occured in Armenia, which tempted the Parthian king beyond his powers of resistance. On the death of Artaxias (B.C. 20), Augustus, who was then in the East, had sent Tiberius into Armenia to arrange matters, and Tiberius had placed upon the throne a brother of Artaxias, named Tigranes. Tigranes died in B.C. 6, and the Armenians, without waiting to know the will of the Roman Emperor, conferred the royal title on his sons, for whose succession he had before his death paved the way by associating them with him in the government. Enraged at this assumption of independence, Augustus sent an expedition into Armenia (B.C. 5), deposed the sons of Tigranes, and established on the throne a certain Artavasdes, whose birth and parentage are not known to us. But the Armenians were not now inclined to submit to foreign dictation; they rose in revolt against Artavasdes (ab. B.C. 2), defeated his Roman supporters, and expelled him from the kingdom. Another Tigranes was made king; and, as it was pretty certain that the Romans would interfere with this new display of the spirit of independence, the Parthians were called in to resist the Roman oppressors. Armenia, was, in fact, too weak to stand alone, and was obliged to lean upon one or other of the two great empires upon her borders. Her people had no clear political foresight, and allowed themselves to veer and fluctuate between the two influences according as the feelings of the hour dictated. Rome had now angered them beyond their very limited powers of endurance, and they flew to Parthia for help, just as on other occasions we shall find them flying to Rome. Phraates could not bring himself to reject the Armenian overtures. Ever since the time of the second Mithridates it had been a settled maxim of Parthian policy to make Armenia dependent; and, even at the cost of a rupture with Rome, it seemed to Phraates that he must respond to the appeal made to him. The rupture might not come. Augustus was now aged, and might submit to the affront without resenting it. He had lately lost the services of his best general, Tiberius, who, indignant at slights put upon him, had gone into retirement at Rhodes. He had no one that he could employ but his grandsons, youths who had not yet fleshed their maiden swords. Phraates probably hoped that Augustus would draw back before the terrors of a Parthian war under such circumstances, and would allow without remonstrance the passing of Armenia into the position of a subject-ally of Parthia.