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 boundary as separating them, they would constitute a power that could not but be irresistible. It would be easy for them to reduce under their sway all the barbarous races on the skirts of their empires, and to hold them in subjection by a flexible system of administration and government. The Roman infantry was the best in the world, and in steady hand-to-hand fighting must be allowed to be unrivalled. The Parthians surpassed all nations in the number of their cavalry and in the excellency of their archers. If these advantages, instead of being separated, were combined, and the various elements on which success in war depends were thus brought into harmonious union, there could be no difficulty in establishing and maintaining a universal monarchy. Were that done, the Parthian spices and rare stuffs, as also the Roman metals and manufactures, would no longer need to be imported secretly and in small quantities by merchants, but, as the two countries would form together but one nation and one state, there would be a free interchange among all the citizens of their various products and commodities.