It might have been expected that an advance would have at once been directed on Ctesiphon, the Parthian capital; but Trajan, for some reason which is not made clear to us, determined otherwise. He repassed the Tigris into Mesopotamia, took Hatra (now el-Hadhr), at that time one of the most considerable places in those parts, and then, crossing to the Euphrates, descended its course to Hit and Babylon. No resistance was offered him, and he became master of the mighty Babylon without a blow. Seleucia seems also to have submitted; and it remained only to attack and take the capital in order to have complete possession of the entire region watered by the two great rivers. For this purpose a fleet was again necessary, and, as the ships used on the upper Tigris had, it would seem, been abandoned, Trajan conveyed a flotilla, which had descended the Euphrates, across Mesopotamia on rollers, and launching it upon the Tigris, proceeded to the attack of the great metropolis. Here again the resistance that he encountered was trivial. Like Babylon and Seleucia, Ctesiphon at once opened its gates. The monarch had departed with his family and his chief treasures,6 and had placed a vast space between himself and his antagonist. He was prepared to contend with his Roman foe, not in battle array, but by means of distance, natural obstacles, and guerilla warfare. He had evidently determined neither to risk a battle nor stand a siege. As Trajan advanced, he retreated, seeming to yield all, but no doubt intending, if it should be necessary, to turn to bay at last, and in the meantime diligently fomenting that spirit of discontent and disaffection which was shortly to render the further advance of the Imperial troops impossible.
But, for the moment, all appeared to go well with the invaders. The surrender of Ctesiphon brought with it the submission of the whole region on the lower courses of the great rivers, and gave the conqueror access to the waters of a new sea. Trajan may be excused if he overrated his successes, regarded himself as another Alexander, and deemed that the great monarchy, so long the rival of Rome, was now at last swept away, and that the entire East was on the point of being absorbed into the Roman Empire. The capture by his lieutenants of the golden throne of the Parthian kings may well have seemed to him emblematic of this change; and the flight of Chosroes into the remote and barbarous regions of the far East may have helped to lull his adversary into a feeling of complete security. Such a feeling is implied in the pleasure voyage of the conqueror down the Tigris to the Persian Gulf, in his embarkation on the waters of the Southern Sea, in the inquiries which he instituted with respect to Indian affairs, and in the regret to which he gave utterance, that his advanced years prevented him from making India the term of his labors. No shadow of his coming troubles seems to have flitted before the eyes of the Emperor during the weeks that he was thus occupied—weeks which he passed in self-complacent contemplation of the past and dreams of an impossible future.
Suddenly, tidings of a most alarming kind dispelled his pleasing visions, and roused him to renewed exertions. Revolt, he found, had broken out everywhere in his rear. At Seleucia, at Hatra, at Nisibis, at Edessa, the natives had flown to arms; his entire line of retreat was beset by foes, and he ran a risk of having his return cut off, and of perishing in the land which he had invaded. Trajan had hastily to retrace his stops, and to send his generals in all directions to check the spread of insurrection. Seleucia was recovered by Erucius Clarus and Julius Alexander, who punished its rebellion by delivering it to the flames. Lucius Quietus retook Nisibis, and plundered and burnt Edessa. Maximus, on the contrary, was defeated and slain by the rebels, who completely destroyed the Roman army under his orders. Trajan, perceiving how slight his hold was upon the conquered populations, felt compelled to change his policy, and, as the only mode of pacifying, even temporarily, the growing discontent, instead of making Lower Mesopotamia into a Roman province, as he had made Armenia, Upper Mesopotamia, and Adiabene (or Assyria), he proceeded with much pomp and display to set up a native king. The prince selected was a certain Parthamaspates, a member of the royal family of the Arsacidse, who had previously sided with Rome against the reigning monarch. In a plain near Ctesiphon, where he had had his tribunal erected, Trajan, after a speech wherein he extolled the greatness of his own exploits, presented to the assembled Romans and natives this youth as King of Parthia, and with his own hand placed the diadem upon his brow.
Under cover of the popularity acquired by this act the aged Emperor now commenced his retreat. The line of the Tigris was no doubt open to him, and along this he might have marched in peace to Upper Mesopotamia or Armenia; but either he preferred the direct route to Syria by way of Hatra and Singara, or the insult offered to the Roman name by the independent attitude which the people of the former place still maintained induced him to diverge from the general line of his course, and to enter the desert in order to chastise their presumption. Hatra was a small town, but strongly fortified. The inhabitants at this time belonged to that Arabian immigration which was always more and more encroaching upon Mesopotamia. They were Parthian subjects, but appear to have had their own native kings. On the approach of Trajan, nothing daunted, they closed their gates, and prepared themselves for resistance. Though he battered down a portion of the wall, they repulsed all the attempts of his soldiers to enter through the breach, and when he himself came near to reconnoitre, they drove him off with their arrows. His troops suffered from the heat, from the want of provisions and fodder, from the swarms of flies which disputed with them every morsel of their food and every drop of their drink, and finally from violent hail and thunderstorms. Trajan was forced to withdraw after a time without effecting anything, and to own himself baffled and defeated by the garrison of a petty fortress.
The year, A.D. 116, seems to have closed with this memorable failure. In the following spring, Chosroes, learning the retreat of the Romans, returned to Ctesiphqn, expelled Parthamaspates, who retired into Roman territory, and re-established his authority in Susiana and Southern Mesopotamia. The Romans, however, still held Assyria (Adiabene) and Upper Mesopotamia, as well as Armenia, and had the strength of the Empire been exerted to maintain these possessions, they might have continued in all probability to be Roman provinces, despite any efforts that Parthia could have made to recover them. But in August, A.D. 117, Trajan died; and his successor, Hadrian, was deeply impressed with the opinion that Trajan’s conquests had been impolitic, and that it was unsafe for Rome to attempt under the circumstances of the time any extension of the Eastern frontier. The first act of Hadrian was to relinquish the three provinces which Trajan’s Parthian war had added to the Empire, and to withdraw the legions within the Euphrates. Assyria and Mesopotamia were at once reoccupied by the Parthians. Armenia appears to have been made over by Hadrian to Parthamaspates, and to have thus returned to its former condition of a semi-independent kingdom, leaning alternately on Rome and Parthia. It has been asserted that Osrhoene was placed likewise upon the same footing; but the numismatic evidence adduced in favor of this view is weak; and upon the whole it appears most probable that, like the other Mesopotamian countries, Osrhoene again fell under the dominion of the Arsacidae. Rome therefore gained nothing by the great exertions which she had made, unless it were a partial recovery of her lost influence in Armenia, and a knowledge of the growing weakness of her Eastern rival—a knowledge which, though it produced no immediate fruit, was of importance, and was borne in mind when, after another half-century of peace, the relations of the two empires became once more unsatisfactory.
The voluntary withdrawal of Hadrian from Assyria and Mesopotamia placed him on amicable terms with Parthia during the whole of his reign. Chosroes and his successor could not but feel themselves under obligations to the monarch who, without being forced to it by a defeat, had restored to Parthia the most valuable of her provinces. On one occasion alone do we hear of any, even threatened, interruption of the friendly relations subsisting between the two powers; and then the misunderstanding, whatever it may have been, was easily rectified and peace maintained. Hadrian, in A.D. 122, had an interview with Chosroes on his eastern frontier, and by personal explanations and assurances averted, we are told, an impending outbreak. Not long afterwards (A.D. 130, probably) he returned to Chosroes the daughter who had been captured by Trajan, and at the same time promised the restoration of the golden throne, on which the Parthians appear to have set a special value.
It must have been soon after he received back his daughter that Chosroes died. His latest coins bear a date equivalent to A.D. 128; and the Roman historians give Volagases II. as king of Parthia in A.D. 133. It has been generally supposed that this prince was Chosroes’ son, and succeeded him in the natural course; but the evidence of the Parthian coins is strong against these suppositions. According to them, Volagases had been a pretender to the Parthian throne as early as A.D. 78, and had struck coins both in that year and the following one, about the date of the accession of Pacorus. His attempt had, however, at that time failed, and for forty-one years he kept his pretensions in abeyance; but about A.D. 119 or 120 he appears to have again come forward, and to have disputed the crown with Chosroes, or reigned contemporaneously with him over some portion of the Parthian kingdom, till about A.D. 130, when—probably on the death of Chosroes—he was acknowledged as sole king by the entire nation. Such is the evidence of the coins, which in this case are very peculiar, and bear the name of Volagases from first to last. It seems to follow from them that Chosroes was succeeded, not by a son, but by a rival, an old claimant of the crown, who cannot have been much younger than Chosroes himself.
CHAPTER XIX.
Reign of Volagases II. Invasion of the Alani. Communications between Volagases and Antoninus Pius. Death of Volagases II. and Accession of Volagases III. Aggressive War of Volagases III. on Rome. Campaign of A.D. 162. Verus sent to the East. Sequel of the War. Losses suffered by Parthia. Death of Volagases III.