Reaction under Hadrian and Pius.For the moment no doubt it was otherwise. The Oriental conquests of Trajan lit up the gloomy evening of the Roman empire like flashes of lightning in the darkness of the night; but, like these, they brought no new morning. His successor found himself compelled to choose between completing the unfinished work of subduing the Parthians or allowing it to drop. The extension of the frontier could not be carried out at all without a considerable increase of the army and of the budget; and the shifting of the centre of gravity to the East, thereby rendered inevitable, was a dubious strengthening of the empire. Hadrian and Pius therefore returned entirely into the paths of the earlier imperial period. Hadrian allowed the Roman vassal-king of Parthia, Parthamaspates, to drop, and portioned him off in another way. He evacuated Assyria and Mesopotamia, and voluntarily gave back these provinces to their earlier ruler. He sent to him as well his captive daughter; the permanent token of the victory won, the golden throne of Ctesiphon, even the pacific Pius refused to deliver up again to the Parthians. Hadrian as well as Pius earnestly endeavoured to live in peace and friendship with their neighbour, and at no time do the commercial relations between the Roman entrepôts on the Syrian east frontier and the mercantile towns on the Euphrates seem to have been more lively than at this epoch.
Armenia a vassal-state.Armenia ceased likewise to be a Roman province, and returned to its former position as a Roman vassal-state and a Parthian appanage of the second son.[54] The princes of the Albani, and the Iberians on the Caucasus, and the numerous small dynasts in the south-eastern corner of the Black Sea likewise remained dependent.[55] Roman garrisons were stationed not merely on the coast in Apsarus[56] and on the Phasis, but, as can be shown, under Commodus in Armenia itself, not far from Artaxata; in a military point of view all these states belonged to the district of the commandant of Cappadocia.[57] This supremacy, however, very indefinite in its nature, seems to have been dealt with generally, and in particular by Hadrian,[58] in such a way that it appeared more as a right of protection than as subjection proper, and at least the more powerful of these princes did, and left undone, in the main what pleased them. The common interest—which we have formerly brought out—in warding off the wild trans-Caucasian tribes became still more definitely prominent in this epoch, and evidently served as a bond in particular between Romans and Parthians. Towards the end of the reign of Hadrian the Alani, in agreement apparently with the king of Iberia, at that time Pharasmanes II., on whom it primarily devolved to bar the pass of the Caucasus against them, invaded the southern regions, and pillaged not only the territory of the Albanians and Armenians, but also the Parthian province of Media and the Roman province of Cappadocia, though matters did not come to a waging of war in common, but the gold of the ruler then reigning in Parthia, Vologasus III., and the mobilising of the Cappadocian army on the part of the Romans,[59] induced the barbarians to return, yet their interests coincided, and the complaint which the Parthians lodged in Rome as to Pharasmanes of Iberia, shows the concert of the two great powers.[60]
Parthian war under Marcus and Verus.The disturbances of the status quo came again from the Parthian side. The suzerainty of the Romans over Armenia played a part in history similar to that of the German empire over Italy; unsubstantial as it was, it was yet constantly felt as an encroachment, and carried within it the danger of war. Already under Hadrian the conflict was imminent; the emperor succeeded in keeping the peace by a personal interview with the Parthian prince. Under Pius the Parthian invasion of Armenia seemed once more impending; his earnest dissuasive was in the first instance successful. But even this most pacific of all emperors, who had it more at heart to save the life of a burgess than to kill a thousand foes, was obliged in the last period of his reign to prepare himself for the attack and to reinforce the armies of the East. Hardly had he closed his eyes (161), when the long-threatening thunder-cloud discharged itself. By command of Vologasus IV. the Persian general Chosroes[61] advanced into Armenia, and placed the Arsacid prince Pacorus on the throne. The governor of Cappadocia Severianus did what was his duty, and led on his part the Roman troops over the Euphrates. At Elegeia, just where a generation before the king Parthomasiris, likewise placed by the Parthians on the Armenian throne, had humbled himself in vain before Trajan, the armies encountered each other; the Roman was not merely beaten but annihilated in a three days’ conflict; the unfortunate general put himself to death, as Varus had formerly done. The victorious Orientals were not content with the occupation of Armenia, but crossed the Euphrates and invaded Syria; the army stationed there was also defeated, and there were fears as to the fidelity of the Syrians. The Roman government had no choice. As the troops of the East showed on this occasion their small capacity for fighting, and were besides weakened and demoralised by the defeat which they had suffered, further legions were despatched to the East from the West, even from the Rhine, and levies were ordered in Italy itself. Lucius Verus, one of the two emperors who shortly before had come to govern, went in person to the East (162) to take up the chief command, and if he, neither warlike nor yet even faithful to his duty, showed himself unequal to the task, and of his deeds in the East hardly anything else is to be told than that he married his niece there and was ridiculed for his theatrical enthusiasm even by the Antiochenes, the governors of Cappadocia and Syria—in the former case first Statius Priscus, then Martius Verus, in the latter Avidius Cassius,[62] the best generals of this epoch—managed the cause of Rome better than the wearer of the crown. Once more, before the armies met, the Romans offered peace; willingly would Marcus have avoided the severe war. But Vologasus abruptly rejected the reasonable proposals; and this time the pacific neighbour was also the stronger. Armenia was immediately recovered; already, in the year 163, Priscus took the capital Artaxata, and destroyed it. Not far from it the new capital of the country, Kainepolis, in Armenia Nôr-Khalakh or Valarshapat (Etshmiazin) was built by the Romans and provided with a strong garrison.[63] In the succeeding year instead of Pacorus Sohaemus, by descent also an Arsacid, but a Roman subject and Roman senator, was nominated as king of Great Armenia.[64] In a legal point of view nothing was changed in Armenia; yet the bonds which joined it to Rome were drawn tighter.
Conflicts in Syria and Mesopotamia.The conflicts in Syria and Mesopotamia were more serious. The line of the Euphrates was obstinately defended by the Parthians; after a keen combat on the right bank at Sura the fortress of Nicephorium (Ragga) on the left was stormed by the Romans. Still more vehemently was the passage at Zeugma contested; but here too victory remained with the Romans in the decisive battle at Europus (Djerabis to the south of Biredjik). They now advanced on their part into Mesopotamia. Edessa was besieged, Dausara not far from it stormed; the Romans appeared before Nisibis; the Parthian general saved himself by swimming over the Tigris. The Romans might from Mesopotamia undertake the march to Babylon. The satraps forsook in part the banners of the defeated great-king; Seleucia, the great capital of the Hellenes on the Euphrates, voluntarily opened its gates to the Romans, but was afterwards burnt down by them, because the burgesses were rightly or wrongly accused of an understanding with the enemy. The Parthian capital, Ctesiphon, was also taken and destroyed; with good reason at the beginning of the year 165 the senate could salute the two rulers as the Parthian grand-victors. In the campaign of this year Cassius even penetrated into Media; but the outbreak of a pestilence, more especially in these regions, decimated the troops and compelled them to return, accelerating perhaps even the conclusion of peace. The result of the war was the cession of the western district of Mesopotamia; the princes of Edessa and of Osrhoene became vassals of Rome, and the town of Carrhae, which had for long Greek leanings, became a free town under Roman protection.[65] As regards extent, especially in presence of the complete success of the war, the increase of territory was moderate, but yet of importance, inasmuch as thereby the Romans gained a footing on the left bank of the Euphrates. We may add that the territories occupied were given back to the Parthians and the status quo was restored. On the whole, therefore, the policy of reserve adopted by Hadrian was now abandoned once more, and there was a return to the course of Trajan. This is the more remarkable, as the government of Marcus certainly cannot be reproached with ambition and longing after aggrandisement; what it did it did under compulsion and in modest limits.
Parthian wars under Severus.The emperor Severus pursued the same course further and more decidedly. The year of the three emperors, 193, had led to the war between the legions of the West and those of the East, and with Pescennius Niger the latter had succumbed. The Roman vassal-princes of the East, and as well the ruler of the Parthians, Vologasus V., son of Sanatrucius, had, as was natural, recognised Niger, and even put their troops at his disposal; the latter had at first gratefully declined, and then, when his cause took a turn to the worse, invoked their aid. The other Roman vassals, above all the prince of Armenia, cautiously kept back; only Abgarus, the prince of Edessa, sent the desired contingent. The Parthians promised aid, and it came at least from the nearest districts, from the prince Barsemias of Hatra in the Mesopotamian desert, and from the satrap of the Adiabeni beyond the Tigris. Even after Niger’s death (194) these strangers not merely remained in the Roman Mesopotamia, but even demanded the withdrawal of the Roman garrisons stationed there and the giving back of this territory.[66]
Province of Mesopotamia.Thereupon Severus advanced into Mesopotamia and took possession of the whole extensive and important region. From Nisibis an expedition was conducted against the Arab prince of Hatra, which, however, did not succeed in taking the fortified town; even beyond the Tigris against the satrap of Adiabene the generals of Severus accomplished nothing of importance.[67] But Mesopotamia, i.e. the whole region between the Euphrates and Tigris as far as the Chaboras, became a Roman province, and was occupied with two legions newly created on account of this extension of territory. The principality of Edessa continued to subsist as a Roman fief, but was now no longer border-territory but surrounded by land directly imperial. The considerable and strong city of Nisibis, thenceforth called after the name of the emperor and organised as a Roman colony, became the capital of the new province and seat of the governor. After an important portion of territory had thus been torn from the Parthian kingdom, and armed force had been used against two satraps dependent on it, the great-king made ready with his troops to oppose the Romans. Severus offered peace, and ceded for Mesopotamia a portion of Armenia. But the decision of arms was thereby only postponed. As soon as Severus had started for the West, whither the complication with his co-ruler in Gaul recalled him, the Parthians broke the peace[68] and advanced into Mesopotamia; the prince of Osrhoene was driven out, the land was occupied, and the governor, Laetus, one of the most excellent warriors of the time, was besieged in Nisibis. He was in great danger, when Severus once more arrived in the East in the year 198, after Albinus had succumbed. Thereupon the fortune of war turned. The Parthians retreated, and now Severus took the offensive. He advanced into Babylonia, and won Seleucia and Ctesiphon; the Parthian king saved himself with a few horsemen by flight, the crown-treasure became the spoil of the victors, the Parthian capital was abandoned to the pillage of the Roman soldiers, and more than 100,000 captives were brought to the Roman slave market. The Arabians indeed in Hatra defended themselves better than the Parthian state itself; in vain Severus endeavoured in two severe sieges to reduce the desert-stronghold. But in the main the success of the two campaigns of 198 and 199 was complete. By the erection of the province of Mesopotamia and of the great command there, Armenia lost the intermediate position which it hitherto had; it might remain in its previous relations and apart from formal incorporation. The land retained thus its own troops, and the imperial government even paid for these subsequently a contribution from the imperial chest.[69]
The change of government in the West and in the East.The further development of these relations as neighbours was essentially influenced by the changes which internal order underwent in the two empires. If under the dynasty of Nerva, and not less under Severus, the Parthian state, often torn asunder by civil war and contention for the crown, had been confronted by the relatively stable Roman monarchy as superior, this order of things broke down after Severus’s death, and almost for a century there followed in the western empire mostly wretched and thoroughly ephemeral regents, who in presence of other countries were constantly hesitating between arrogance and weakness. While the scale of the West thus sank that of the East rose. A few years after the death of Severus (211) a revolution took place in Iran, which not merely, like so many earlier crises, overthrew the ruling regent, nor even merely called to the government another dynasty instead of the decayed Arsacids, but, unchaining the national and religious elements for a mightier upward flight, substituted for the bastard civilisation—pervaded by Hellenism—of the Parthian state the state-organisation, faith, manners, and princes of that province which had created the old Persian empire, and, since its transition to the Parthian dynasty, preserved within it as well the tombs of Darius and Xerxes as the germs of the regeneration of the people. The re-establishment of the great-kingdom of the Persians overthrown by Alexander ensued through the emergence of the dynasty of the Sassanids. Let us cast a glance at this new shape of things before we pursue further the course of Romano-Parthian relations in the East.
The Sassanids.It has already been stated that the Parthian dynasty, although it had wrested Iran from Hellenism, was yet regarded by the nation as, so to speak, illegitimate. Artahshatr, or in new Persian Ardashir—so the official biography of the Sassanids reports—came forward to revenge the blood of Dara murdered by Alexander, and to bring back the rule to the legitimate family and re-establish it, such as it had been at the time of his forefathers before the divisional kings. Under this legend lies a good deal of reality. The dynasty which bears the name of Sasan, the grandfather of Ardashir, was no other than the royal dynasty of the Persian province; Ardashir’s father, Papak or Pabek,[70] and a long list of his ancestors had, under the supremacy of the Arsacids, swayed the sceptre in this ancestral land of the Iranian nation,[71] had resided in Istachr, not far from the old Persepolis, and marked their coins with Iranian language and Iranian writing, and with the sacred emblems of the Persian national faith, while the great-kings had their abode in the half-Greek border-land, and had their coins stamped in the Greek language and after the Greek style. The fundamental organisation of the Iranian state-system—the great-kingdom holding superiority over the divisional kings—was under the two dynasties as little different as that of the empire of the German nation under the Saxon and the Suabian emperors. Only for this reason in that official version the time of the Arsacids is designated as that of the divisional-kings, and Ardashir as the first common head of all Iran after the last Darius, because in the old Persian empire the Persian province stood related alike to the other provinces and to the Parthians, as in the Roman state Italy stood related to the provinces, and the Persian disputed with the Parthian the legitimate title to the great-kingdom connected de jure with his province.[72]
Extent of the Sassanid kingdom.What was the relation of the Sassanid kingdom to that of the Arsacids in point of extent, is a question to which tradition gives no sufficient answer. The provinces of the west collectively remained subject to the new dynasty after it sat firm in the saddle, and the claims which it set up against the Romans went, as we shall see, far beyond the pretensions of the Arsacids. But how far the rule of the Sassanids reached towards the West, and when it advanced to the Oxus which was subsequently regarded as the legitimate boundary between Iran and Turan, are matters withdrawn from our field of vision.[73]