Sapor’s second war with Rome was, like his first, provoked by himself.  After concluding his peace with Philip, he had seen the Roman world governed successively by six weak emperors, of whom four had died violent deaths, while at the same time there had been a continued series of attacks upon the northern frontiers of the empire by Alemanni, Goths, and Franks, who had ravaged at their will a number of the finest provinces, and threatened the absolute destruction of the great monarchy of the West.  It was natural that the chief kingdom of Western Asia should note these events, and should seek to promote its own interests by taking advantage of the circumstances of the time.  Sapor, in A.D. 258, determined on a fresh invasion of the Roman provinces, and, once more entering Mesopotamia, carried all before him, became master of Nisibis, Carrhae, and Edessa, and, crossing the Euphrates, surprised Antioch, which was wrapped in the enjoyment of theatrical and other representations, and only knew its fate on the exclamation of a couple of actors “that the Persians were in possession of the town.”  The aged emperor, Valerian, hastened to the protection of his more eastern territories, and at first gained some successes, retaking Antioch, and making that city his headquarters during his stay in the East.  But, after this, the tide turned.  Valerian entrusted the whole conduct of the war to Macrianus, his Praetorian prefect, whose talents he admired, and of whose fidelity he did not entertain a suspicion.  Macrianus, however, aspired to the empire, and intentionally brought Valerian into difficulties, in the hope of disgracing or removing him.  His tactics were successful.  The Roman army in Mesopotamia was betrayed into a situation whence escape was impossible, and where its capitulation was only a question of time.  A bold attempt’ made to force a way through the enemy’s lines failed utterly, after which famine and pestilence began to do their work.  In vain did the aged emperor send envoys to propose a peace, and offer to purchase escape by the payment of an immense sum in gold.  Sapor, confident of victory, refused the overture, and, waiting patiently till his adversary was at the last gasp, invited him to a conference, and then treacherously seized his person.  The army surrendered or dispersed.  Macrianus, the Praetorian prefect, shortly assumed the title of emperor, and marched against Gallienus, the son and colleague of Valerian, who had been left to direct affairs in the West.  But another rival started up in the East.  Sapor conceived the idea of complicating the Roman affairs by himself putting forward a pretender; and an obscure citizen of Antioch, a certain Miriades or Cyriades, a refugee in his camp, was invested with the purple, and assumed the title of Caesar. [PLATE.  XIII.]

[Illustration:  PLATE 13.]