The accession of Phraataces made no difference in the attitude of Parthia towards Armenia.  The young prince was as anxious as his father had been to maintain the Parthian claims to that country, and at first perhaps as inclined to believe that Augustus would not dispute them.  Immediately upon his accession he sent ambassadors to Rome announcing the fact, apologizing for the circumstances under which it had taken place, and proposing a renewal of the peace which had subsisted between Augustus and his father.  Apparently, he said nothing about Armenia, but preferred a demand for the surrender of his four brothers, whom no doubt he designed to destroy.  The answer of Augustus was severe in the extreme.  Addressing Phraataces by his bare name, without adding the title of king, he required him to lay aside the royal appellation, which he had arrogantly and without any warrant assumed, and at the same time to withdraw his forces from Armenia.  On the surrender of the Parthian princes he kept silence, ignoring a demand which he had no intention of according.  It was clearly his design to set up one of the elder brothers as a rival claimant to Phraataces, or at any rate to alarm him with the notion that, unless he made concessions, this policy would be adopted.  But Phraataces was not to be frightened by a mere message.  He responded to Augustus after his own fashion, dispatching to him a letter wherein he took to himself the favorite Parthian title of “king of kings,” and addressed the Roman Emperor simply as “Caesar.”  The attitude of defiance would no doubt have been maintained, had Augustus confined himself to menaces; when, however, it appeared that active measures would be taken, when Augustus, in B.C. 1, sent his grandson, Caius, to the East with orders to re-establish the Roman influence in Armenia even at the cost of a Parthian war, and that prince showed himself in Syria with all the magnificent surroundings of the Imperial dignity, the Parthian monarch became alarmed.  He had an interview with Caius in the spring of A.D. 1, upon an island in the Euphrates; where the terms of an arrangement between the two Empires were discussed and settled.  The armies of the two chiefs were drawn up on the opposite banks of the river, facing one another; and the chiefs themselves, accompanied by an equal number of attendants, proceeded to deliberate in the sight of both hosts.  Satisfactory pledges having been given by the Parthian monarch, the prince and king in turn entertained each other on the borders of their respective dominions; and Caius returned into Syria, having obtained an engagement from the Parthians to abstain from any further interference with Armenian affairs.  The engagement appears to have been honorably kept; for when, shortly afterward, fresh complications occurred, and Caius in endeavoring to settle them received his death-wound before the walls of an Armenian tower, we do not hear of Parthia as in any way involved in the unfortunate occurrence.  The Romans and their partisans in the country were left to settle the Armenian succession as they pleased; and Parthia kept herself wholly aloof from the matters transacted upon her borders.