was the act of the Persians.  The retreat was then exchanged for an advance, and after a brief engagement the Romans were victorious, and inflicted a severe loss upon their adversaries.  But the success was not followed by results of any importance.  Neither side seems to have been anxious for another general encounter; and the season for hostilities was occupied by a sort of guerilla warfare, in which the advantage rested alternately with the Persians and the Romans.  At length, when the summer was ended, the commanders on either side entered into negotiations; and a truce was made which allowed Sapor to retire to Ctesiphon, and the Roman emperor, who was now personally directing the war, to go into winter quarters at Antioch.

After this the war languished for two or three years.  Valens was wholly deficient in military genius, and was quite content if he could maintain a certain amount of Roman influence in Armenia and Iberia, while at the same time he protected the Roman frontier against Persian invasion.  Sapor was advanced in years, and might naturally desire repose, having been almost constantly engaged in military expeditions since he reached the age of sixteen.  Negotiations seem to have alternated with hostilities during the interval between A.D. 371 and 376; but they resulted in nothing, until, in this last-named year, a peace was made, which gave tranquillity to the East during the remainder of the reign of Sapor.

The terms upon which this peace was concluded are obscure.  It is perhaps most probable that the two contracting powers agreed to abstain from further interference with Iberia and Armenia, and to leave those countries to follow their own inclinations.  Armenia seems by the native accounts to have gravitated towards Rome under these circumstances, and Iberia is likely to have followed her example.  The tie of Christianity attached these countries to the great power of the West; and, except under compulsion, they were not likely at this time to tolerate the yoke of Persia for a day.  When Jovian withdrew the Roman protection from them, they were forced for a while to submit to the power which they disliked; but no sooner did his successors reverse his policy, and show themselves ready to uphold the Armenians and Iberians against Persia, than they naturally reverted to the Roman side, and formed an important support to the empire against its Eastern rival.

The death of Sapor followed the peace of A.D. 376 within a few years.  He died A.D. 379 or 380, after having reigned seventy years.  It is curious that, although possessing the crown for so long a term, and enjoying a more brilliant reign than any preceding monarch, he neither left behind him any inscriptions, nor any sculptured memorials.  The only material evidences that we possess of his reign are his coins, which are exceedingly numerous.  According to Mordtmann, they may be divided into three classes, corresponding to three periods in his life.  The