It appears that the Roman generals, in pursuance of the orders given them, marched across Northern Mesopotamia to the Armenian borders, and were there joined by an Armenian contingent which Arsaces sent to their assistance.  The allies marched together into Media, and carried fire and sword through the fruitful district known as Chiliacomus, or “the district of the Thousand Villages.”  They might easily have advanced further; but the Armenians suddenly and without warning drew off and fell back towards their own country.  According to Moses of Chorene, their general, Zurseus, was actuated by a religious motive; it seemed to him monstrous that Armenia, a Christian country, should embrace the cause of an apostate, and he was prepared to risk offending his own sovereign rather than lend help to one whom he regarded as the enemy of his faith.  The Roman generals, thus deserted by their allies, differed as to the proper course to pursue.  While one was still desirous of descending the course of the Tigris, and making at least an attempt to effect a junction with Julian, the other forbade his soldiers to join in the march, and insisted on falling back and re-entering Mesopotamia.  As usual in such cases, the difference of opinion resulted in a policy of inaction.  The attempt to join Julian was given up; and the second army, from which he had hoped so much, played no further part in the campaign of A.D. 363.

We are told that Julian heard of the defection of the Armenians while he was still on his way to Ctesiphon, and immediately sent a letter to Arsacos, complaining of his general’s conduct, and threatening to exact a heavy retribution on his return from the Persian war, if the offence of Zurseus were not visited at once with condign punishment.  Arsaces was greatly alarmed at the message; and, though he made no effort to supply the shortcomings of his officer by leading or sending fresh troops to Julian’s assistance, yet he hastened to acquit himself of complicity in the misconduct of Zurseus by executing him, together with his whole family.  Having thus, as he supposed, secured himself against Julian’s anger, he took no further steps, but indulged his love of ease and his distaste for the Roman alliance by remaining wholly passive during the rest of the year.

But though the attitude taken by Armenia was thus, on the whole, favorable to the Persians,and undoubtedly contributed to Sapor’s success, he was himself so far from satisfied with the conduct of Arsaces that he resolved at once to invade his country and endeavor to strip him of his crown.  As Rome had by the recent treaty relinquished her protectorate over Armenia, and bound herself not to interfere in any quarrel between the Armenians and the Persians, an opportunity was afforded for bringing Armenia into subjection which an ambitious monarch like Sapor was not likely to let slip.  He had only to consider whether he would employ art or violence, or whether he would rather prefer a judicious admixture of the