Constantius reoccupied Edessa, and had (we are told) some thoughts of renewing the siege of Bezabde; actually, however, he did not advance further, but contented himself with sending a part of his army to watch Sapor, giving them strict orders not to risk an engagement.

Sapor, on his side, began the year with demonstrations which were taken to mean that he was about to pass the Euphrates; but in reality he never even brought his troops across the Tigris, or once set foot in Mesopotamia.

After wasting weeks or months in a futile display of his armed strength upon the eastern bank of the river, and violently alarming the officers sent by Constantius to observe his movements, he suddenly, towards autumn, withdrew his troops, having attempted nothing, and quietly returned to his capital! It is by no means difficult to understand the motives which actuated Constantius.
He was, month after month, receiving intelligence from the West of steps taken by Julian which amounted to open rebellion, and challenged him to engage in civil war.

So long as Sapor threatened invasion he did not like to quit Mesopotamia, lest he might appear to have sacrificed the interests of his country to his own private quarrels; but he must have been anxious to return to the seat of empire from the first moment that intelligence reached him of Julian's assumption of the imperial name and dignity; and when Sapor's retreat was announced he naturally made all haste to reach his capital.

Meanwhile the desire of keeping his army intact caused him to refrain from any movement which involved the slightest risk of bringing on a battle, and, in fact, reduced him to inaction.