The successor of Varahan V. was his son, Isdigerd the Second, who ascended the Persian throne without opposition in the year A.D. 440.  His first act was to declare war against Rome.  The Roman forces were, it would seem, concentrated in the vicinity of Nisibis; and Isdigerd may have feared that they would make an attack upon the place.  He therefore anticipated them, and invaded the empire with an army composed in part of his own subjects, but in part also of troops from the surrounding nations.  Saracens, Tzani, Isaurians, and Huns (Ephthalites?) served under his standard; and a sudden incursion was made into the Roman territory, for which the imperial officers were wholly unprepared.  A considerable impression would probably have been produced, had not the weather proved exceedingly unpropitious.  Storms of rain and hail hindered the advance of the Persian troops, and allowed the Roman generals a breathing space, during which they collected an army.  But the Emperor Theodosius was anxious that the flames of war should not be relighted in this quarter; and his instructions to the prefect of the East, the Count Anatolius, were such as speedily led to the conclusion, first of a truce for a year, and then of a lasting treaty.  Anatolius repaired as ambassador to the Persian camp, on foot and alone, so as to place himself completely in Isdigerd’s power—­an act which so impressed the latter that (we are told) he at once agreed to make peace on the terms which Anatolius suggested.  The exact nature of these terms is not recorded; but they contained at least one unusual condition.  The Romans and Persians agreed that neither party should construct any new fortified post in the vicinity of the other’s territory—­a loose phrase which was likely to be variously interpreted, and might easily lead to serious complications.

It is difficult to understand this sudden conclusion of peace by a young prince, evidently anxious to reap laurels, who in the first year of his reign had, at the head of a large army, invaded the dominions of a neighbor.  The Roman account, that he invaded, that he was practically unopposed, and that then, out of politeness towards the prefect of the East, he voluntarily retired within his own frontier, “having done nothing disagreeable,” is as improbable a narrative as we often meet with, even in the pages of the Byzantine historians.  Something has evidently been kept back.  If Isdigerd returned, as Procopius declares, without effecting anything, he must have been recalled by the occurrence of troubles in some other part of his empire.  But it is, perhaps, as likely that he retired, simply because he had effected the object with which he engaged in the war.  It was a constant practice of the Romans to advance their frontier by building strong towns on or near a debatable border, which attracted to them the submission of the neighboring district.  The recent building of Theodosiopolis in the eastern part of Roman Armenia had been an instance of this practice.  It was perhaps being pursued elsewhere along the Persian border, and the invasion of Isdigerd may have been intended to check it.  If so, the proviso of the treaty recorded by Procopius would have afforded him the security which he required, and have rendered it unnecessary for him to continue the war any longer.