Artabanus soon became aware of the intrigue.  He found that the chief conspirators in Parthia were a certain Sinnaces, a nobleman distinguished alike for his high birth and his great riches, and a eunuch named Abdus, who held a position about the court, and was otherwise a personage of importance.  It would have been easy to seize these two men, and execute them; but Artabanus was uncertain how far the conspiracy extended, and thought it most prudent to defer bringing matters to a crisis.  He therefore dissembled, and was content to cause a delay, first by administering to Abdus a slow poison, and then by engaging Sinnaces so constantly in affairs of state that he had little or no time to devote to plotting.  Successful thus far by his own cunning and dexterity, he was further helped by a stroke of good fortune, on which he could not have calculated.  Phraates, who thought that after forty years of residence in Rome it was necessary to fit himself for the position of Parthian king by resuming the long-disused habits of his nation, was carried off, after a short residence in Syria, by a disease which he was supposed to have contracted through the change in his mode of life.  His death must for the time have paralyzed the conspirators, and have greatly relieved Artabanus.  It was perhaps now, under the stimulus of a sudden change from feelings of extreme alarm to fancied security, that he wrote the famous letter to Tiberius, in which he reproached him for his cruelty, cowardice, and luxuriousness of living, and recommended him to satisfy the just desires of the subjects who hated him by an immediate suicide.

This letter, if genuine, must be pronounced under any circumstances a folly; and if really sent at this time, it may have had tragical consequences.  It is remarkable that Tiberius, on learning the death of Phraates, instead of relaxing, intensified his efforts.  Not only did he at once send out to Syria another pretender, Tiridates, a nephew of the deceased prince, in order to replace him, but he made endeavors, such as we do not hear of before, to engage other nations in the struggle; and further, he enlarged the commission of Vitellius, giving him a general superintendence over the affairs of the East.  Thus Artabanus found himself in greater peril than ever, and if he had really indulged in the silly effusion ascribed to him was rightly punished.  Pharasmanes, king of Iberia, a portion of the modern Georgia, incited by Tiberius, took the field (A.D. 35), and proclaimed his intention of placing his brother, Mithridates, on the Armenian throne.  Having by corruption succeeded in bringing about the murder of Arsaces by his attendants, he marched into Armenia, and became master of the capital without meeting any resistance.  Artabanus, upon this, sent his son Orodes to maintain the Parthian cause in the disputed province; but he proved no match for the Iberian, who was superior in numbers, in the variety of his troops, and in familiarity