On the death of Volagases IV., the Parthian crown was disputed between his two sons, Artabanus and Volagases.  According to the classical writers, the contest resulted in favor of the former, whom they regard as undisputed sovereign of the Parthians, at any rate from the year A.D. 216.  It appears, however, from the Parthian coins, that both the brothers claimed and exercised sovereignty during the entire term of seventeen or eighteen years which intervened between the death of Volagases IV. and the revolt of the Persians.  Artabanus must beyond all doubt have acquired the sole rule in the western portions of the empire, since (from A.D. 216 to A.D. 226) he was the only monarch known to the Romans.  But Volagases may at the same time have been recognized in the more eastern provinces, and may have maintained himself in power in those remote regions without interfering with his brother’s dominion in the West.  Still this division of the empire must naturally have tended to weaken it; and the position of Volagases has to be taken into account in estimating the difficulties under which the last monarch of the Arsacid series found himself placed—­difficulties to which, after a struggle, he was at last forced to succumb.  Domestic dissension, wars with a powerful neighbor (Rome), and internal disaffection and rebellion formed a combination, against which the last Parthian monarch, albeit a man of considerable energy, strove in vain.  But he strove bravely; and the closing scenes of the empire, in which he bore the chief part, are not unworthy of its best and palmiest days.

An actual civil war appears to have raged between the two brothers for some years.  Caracallus, who in A.D. 211 succeeded his father, Severus, as Emperor of Rome, congratulated the Senate in A.D. 212 on the strife still going on in Parthia, which could not fail (he said) to inflict serious injury on that hostile state.  The balance of advantage seems at first to have inclined towards Volagases, whom Caracallus acknowledged as monarch of Parthia in the year A.D. 215.  But soon after this the fortune of war must have turned; for subsequently to the year A.D. 215, we hear nothing more of Volagases, but find Caracallus negotiating with Artabanus instead, and treating with him as undisputed monarch of the entire Parthian empire.  That this was not his real position, appears from the coins; but the classical evidence may be accepted as showing that from the year A.D. 216, Volagases ceased to have much power, sinking from the rank of a rival monarch into that of a mere pretender, who may have caused some trouble to the established sovereign, but did not inspire serious alarm.