Artabanus, having succeeded in reducing his brother to this condition, and obtained a general acknowledgment of his claims, found himself almost immediately in circumstances of much difficulty.  From the moment of his accession, Caracallus had exhibited an inordinate ambition; and this ambition had early taken the shape of a special desire for the glory of Oriental conquests.  The weak and dissolute son of Severus fancied himself, and called himself, a second Alexander; and thus he was in honor bound to imitate that hero’s marvellous exploits.  The extension of the Roman territory towards the East became very soon his great object, and he shrank from no steps, however base and dishonorable, which promised to conduce towards the accomplishment of his wishes.  As early as A.D. 212 he summoned Abgarus, the tributary king of Osrhoene, into his presence, and when he unsuspectingly complied, seized him, threw him into prison, and declaring his territories forfeited, reduced them into the form of a Roman province.  Successful in this bold proceeding, he attempted to deal with Armenia in the same way; but, though the monarch fell foolishly into the trap set for him, the nation was not so easily managed.  The Armenians flew to arms on learning the imprisonment of their king and royal family; and when, three year afterwards (A.D. 215), Caracallus sent a Roman army under Theocritus, one of his favorites, to chastise them, they inflicted a severe defeat on their assailant.  But the desire of Caracallus to effect Oriental conquests was increased, rather than diminished, by this occurrence.  He had sought a quarrel with Parthia as early as A.D. 214, when he demanded of Volagases the surrender of two refugees of distinction.  The rupture, which he courted, was deferred by the discreditable compliance of the Great King with his requisition.

Volagases surrendered the two unfortunates; and the Roman Emperor was compelled to declare himself satisfied with the concession.  But a year had not elapsed before he had devised a new plan of attack and proceeded to put it in execution.

Volagases V. was about this time compelled to yield the western capital to his brother; and Artabanus IV. became the representative of Parthian power in the eyes of the Romans.  Caracallus in the summer of A.D. 215, having transferred his residence from Nicomedia to Antioch, sent ambassadors from the last-named place to Artabanus, who were to present the Parthian monarch with presents of unusual magnificence, and to make him an unheard-of proposition.  “The Roman Emperor,” said the despatch with which they were intrusted, “could not fitly wed the daughter of a subject or accept the position of son-in-law to a private person.  No one could be a suitable wife to him who was not a princess.”  He therefore asked the Parthian monarch for the hand of his daughter.  Rome and Parthia divided between them the sovereignty of the world; united, as they would be by this marriage, no longer recognizing any