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 two.