While the Roman emperor and the Persian monarch, at the distance of three thousand miles, defended their extreme limits against the Barbarians of the Danube and of the Oxus, their intermediate frontier experienced the vicissitudes of a languid war, and a precarious truce. Two of the eastern ministers of Constantius, the Prætorian præfect Musonian, whose abilities were disgraced by the want of truth and integrity, and Cassian, duke of Mesopotamia, a hardy and veteran soldier, opened a secret negotiation with the satrap Tamsapor. These overtures of peace, translated into the servile and flattering language of Asia, were transmitted to the camp of the Great King; who resolved to signify, by an ambassador, the terms which he was inclined to grant to the suppliant Romans. Narses, whom he invested with that character, was honorably received in his passage through Antioch and Constantinople: he reached Sirmium after a long journey, and, at his first audience, respectfully unfolded the silken veil which covered the haughty epistle of his sovereign. Sapor, King of Kings, and Brother of the Sun and Moon, (such were the lofty titles affected by Oriental vanity,) expressed his satisfaction that his brother, Constantius Cæsar, had been taught wisdom by adversity. As the lawful successor of Darius Hystaspes, Sapor asserted, that the River Strymon, in Macedonia, was the true and ancient boundary of his empire; declaring, however, that as an evidence of his moderation, he would content himself with the provinces of Armenia and Mesopotamia, which had been fraudulently extorted from his ancestors. He alleged, that, without the restitution of these disputed countries, it was impossible to establish any treaty on a solid and permanent basis; and he arrogantly threatened, that if his ambassador returned in vain, he was prepared to take the field in the spring, and to support the justice of his cause by the strength of his invincible arms. Narses, who was endowed with the most polite and amiable manners, endeavored, as far as was consistent with his duty, to soften the harshness of the message. Both the style and substance were maturely weighed in the Imperial council, and he was dismissed with the following answer: "Constantius had a right to disclaim the officiousness of his ministers, who had acted without any specific orders from the throne: he was not, however, averse to an equal and honorable treaty; but it was highly indecent, as well as absurd, to propose to the sole and victorious emperor of the Roman world, the same conditions of peace which he had indignantly rejected at the time when his power was contracted within the narrow limits of the East: the chance of arms was uncertain; and Sapor should recollect, that if the Romans had sometimes been vanquished in battle, they had almost always been successful in the event of the war." A few days after the departure of Narses, three ambassadors were sent to the court of Sapor, who was already returned from the Scythian expedition to his ordinary residence of Ctesiphon. A count, a notary, and a sophist, had been selected for this important commission; and Constantius, who was secretly anxious for the conclusion of the peace, entertained some hopes that the dignity of the first of these ministers, the dexterity of the second, and the rhetoric of the third, would persuade the Persian monarch to abate of the rigor of his demands. But the progress of their negotiation was opposed and defeated by the hostile arts of Antoninus, a Roman subject of Syria, who had fled from oppression, and was admitted into the councils of Sapor, and even to the royal table, where, according to the custom of the Persians, the most important business was frequently discussed. The dexterous fugitive promoted his interest by the same conduct which gratified his revenge. He incessantly urged the ambition of his new master to embrace the favorable opportunity when the bravest of the Palatine troops were employed with the emperor in a distant war on the Danube. He pressed Sapor to invade the exhausted and defenceless provinces of the East, with the numerous armies of Persia, now fortified by the alliance and accession of the fiercest Barbarians. The ambassadors of Rome retired without success, and a second embassy, of a still more honorable rank, was detained in strict confinement, and threatened either with death or exile.
The military historian, who was himself despatched to observe the army of the Persians, as they were preparing to construct a bridge of boats over the Tigris, beheld from an eminence the plain of Assyria, as far as the edge of the horizon, covered with men, with horses, and with arms. Sapor appeared in the front, conspicuous by the splendor of his purple. On his left hand, the place of honor among the Orientals, Grumbates, king of the Chionites, displayed the stern countenance of an aged and renowned warrior. The monarch had reserved a similar place on his right hand for the king of the Albanians, who led his independent tribes from the shores of the Caspian. * The satraps and generals were distributed according to their several ranks, and the whole army, besides the numerous train of Oriental luxury, consisted of more than one hundred thousand effective men, inured to fatigue, and selected from the bravest nations of Asia. The Roman deserter, who in some measure guided the councils of Sapor, had prudently advised, that, instead of wasting the summer in tedious and difficult sieges, he should march directly to the Euphrates, and press forwards without delay to seize the feeble and wealthy metropolis of Syria. But the Persians were no sooner advanced into the plains of Mesopotamia, than they discovered that every precaution had been used which could retard their progress, or defeat their design. The inhabitants, with their cattle, were secured in places of strength, the green forage throughout the country was set on fire, the fords of the rivers were fortified by sharp stakes; military engines were planted on the opposite banks, and a seasonable swell of the waters of the Euphrates deterred the Barbarians from attempting the ordinary passage of the bridge of Thapsacus. Their skilful guide, changing his plan of operations, then conducted the army by a longer circuit, but through a fertile territory, towards the head of the Euphrates, where the infant river is reduced to a shallow and accessible stream. Sapor overlooked, with prudent disdain, the strength of Nisibis; but as he passed under the walls of Amida, he resolved to try whether the majesty of his presence would not awe the garrison into immediate submission. The sacrilegious insult of a random dart, which glanced against the royal tiara, convinced him of his error; and the indignant monarch listened with impatience to the advice of his ministers, who conjured him not to sacrifice the success of his ambition to the gratification of his resentment. The following day Grumbates advanced towards the gates with a select body of troops, and required the instant surrender of the city, as the only atonement which could be accepted for such an act of rashness and insolence. His proposals were answered by a general discharge, and his only son, a beautiful and valiant youth, was pierced through the heart by a javelin, shot from one of the balistæ. The funeral of the prince of the Chionites was celebrated according to the rites of the country; and the grief of his aged father was alleviated by the solemn promise of Sapor, that the guilty city of Amida should serve as a funeral pile to expiate the death, and to perpetuate the memory, of his son.
The ancient city of Amid or Amida, which sometimes assumes the provincial appellation of Diarbekir, is advantageously situate in a fertile plain, watered by the natural and artificial channels of the Tigris, of which the least inconsiderable stream bends in a semicircular form round the eastern part of the city. The emperor Constantius had recently conferred on Amida the honor of his own name, and the additional fortifications of strong walls and lofty towers. It was provided with an arsenal of military engines, and the ordinary garrison had been reenforced to the amount of seven legions, when the place was invested by the arms of Sapor. His first and most sanguine hopes depended on the success of a general assault. To the several nations which followed his standard, their respective posts were assigned; the south to the Vertæ; the north to the Albanians; the east to the Chionites, inflamed with grief and indignation; the west to the Segestans, the bravest of his warriors, who covered their front with a formidable line of Indian elephants. The Persians, on every side, supported their efforts, and animated their courage; and the monarch himself, careless of his rank and safety, displayed, in the prosecution of the siege, the ardor of a youthful soldier. After an obstinate combat, the Barbarians were repulsed; they incessantly returned to the charge; they were again driven back with a dreadful slaughter, and two rebel legions of Gauls, who had been banished into the East, signalized their undisciplined courage by a nocturnal sally into the heart of the Persian camp. In one of the fiercest of these repeated assaults, Amida was betrayed by the treachery of a deserter, who indicated to the Barbarians a secret and neglected staircase, scooped out of the rock that hangs over the stream of the Tigris. Seventy chosen archers of the royal guard ascended in silence to the third story of a lofty tower, which commanded the precipice; they elevated on high the Persian banner, the signal of confidence to the assailants, and of dismay to the besieged; and if this devoted band could have maintained their post a few minutes longer, the reduction of the place might have been purchased by the sacrifice of their lives. After Sapor had tried, without success, the efficacy of force and of stratagem, he had recourse to the slower but more certain operations of a regular siege, in the conduct of which he was instructed by the skill of the Roman deserters. The trenches were opened at a convenient distance, and the troops destined for that service advanced under the portable cover of strong hurdles, to fill up the ditch, and undermine the foundations of the walls. Wooden towers were at the same time constructed, and moved forwards on wheels, till the soldiers, who were provided with every species of missile weapons, could engage almost on level ground with the troops who defended the rampart. Every mode of resistance which art could suggest, or courage could execute, was employed in the defence of Amida, and the works of Sapor were more than once destroyed by the fire of the Romans. But the resources of a besieged city may be exhausted. The Persians repaired their losses, and pushed their approaches; a large preach was made by the battering-ram, and the strength of the garrison, wasted by the sword and by disease, yielded to the fury of the assault. The soldiers, the citizens, their wives, their children, all who had not time to escape through the opposite gate, were involved by the conquerors in a promiscuous massacre.
But the ruin of Amida was the safety of the Roman provinces. As soon as the first transports of victory had subsided, Sapor was at leisure to reflect, that to chastise a disobedient city, he had lost the flower of his troops, and the most favorable season for conquest. Thirty thousand of his veterans had fallen under the walls of Amida, during the continuance of a siege, which lasted seventy-three days; and the disappointed monarch returned to his capital with affected triumph and secret mortification. It is more than probable, that the inconstancy of his Barbarian allies was tempted to relinquish a war in which they had encountered such unexpected difficulties; and that the aged king of the Chionites, satiated with revenge, turned away with horror from a scene of action where he had been deprived of the hope of his family and nation. The strength as well as the spirit of the army with which Sapor took the field in the ensuing spring was no longer equal to the unbounded views of his ambition. Instead of aspiring to the conquest of the East, he was obliged to content himself with the reduction of two fortified cities of Mesopotamia, Singara and Bezabde; the one situate in the midst of a sandy desert, the other in a small peninsula, surrounded almost on every side by the deep and rapid stream of the Tigris. Five Roman legions, of the diminutive size to which they had been reduced in the age of Constantine, were made prisoners, and sent into remote captivity on the extreme confines of Persia. After dismantling the walls of Singara, the conqueror abandoned that solitary and sequestered place; but he carefully restored the fortifications of Bezabde, and fixed in that important post a garrison or colony of veterans; amply supplied with every means of defence, and animated by high sentiments of honor and fidelity. Towards the close of the campaign, the arms of Sapor incurred some disgrace by an unsuccessful enterprise against Virtha, or Tecrit, a strong, or, as it was universally esteemed till the age of Tamerlane, an impregnable fortress of the independent Arabs.
The defence of the East against the arms of Sapor required and would have exercised, the abilities of the most consummate general; and it seemed fortunate for the state, that it was the actual province of the brave Ursicinus, who alone deserved the confidence of the soldiers and people. In the hour of danger, Ursicinus was removed from his station by the intrigues of the eunuchs; and the military command of the East was bestowed, by the same influence, on Sabinian, a wealthy and subtle veteran, who had attained the infirmities, without acquiring the experience, of age. By a second order, which issued from the same jealous and inconstant councils, Ursicinus was again despatched to the frontier of Mesopotamia, and condemned to sustain the labors of a war, the honors of which had been transferred to his unworthy rival. Sabinian fixed his indolent station under the walls of Edessa; and while he amused himself with the idle parade of military exercise, and moved to the sound of flutes in the Pyrrhic dance, the public defence was abandoned to the boldness and diligence of the former general of the East. But whenever Ursicinus recommended any vigorous plan of operations; when he proposed, at the head of a light and active army, to wheel round the foot of the mountains, to intercept the convoys of the enemy, to harass the wide extent of the Persian lines, and to relieve the distress of Amida; the timid and envious commander alleged, that he was restrained by his positive orders from endangering the safety of the troops. Amida was at length taken; its bravest defenders, who had escaped the sword of the Barbarians, died in the Roman camp by the hand of the executioner: and Ursicinus himself, after supporting the disgrace of a partial inquiry, was punished for the misconduct of Sabinian by the loss of his military rank. But Constantius soon experienced the truth of the prediction which honest indignation had extorted from his injured lieutenant, that as long as such maxims of government were suffered to prevail, the emperor himself would find it is no easy task to defend his eastern dominions from the invasion of a foreign enemy. When he had subdued or pacified the Barbarians of the Danube, Constantius proceeded by slow marches into the East; and after he had wept over the smoking ruins of Amida, he formed, with a powerful army, the siege of Bezabde. The walls were shaken by the reiterated efforts of the most enormous of the battering-rams; the town was reduced to the last extremity; but it was still defended by the patient and intrepid valor of the garrison, till the approach of the rainy season obliged the emperor to raise the siege, and ingloriously to retreat into his winter quarters at Antioch. The pride of Constantius, and the ingenuity of his courtiers, were at a loss to discover any materials for panegyric in the events of the Persian war; while the glory of his cousin Julian, to whose military command he had intrusted the provinces of Gaul, was proclaimed to the world in the simple and concise narrative of his exploits.
In the blind fury of civil discord, Constantius had abandoned to the Barbarians of Germany the countries of Gaul, which still acknowledged the authority of his rival. A numerous swarm of Franks and Alemanni were invited to cross the Rhine by presents and promises, by the hopes of spoil, and by a perpetual grant of all the territories which they should be able to subdue. But the emperor, who for a temporary service had thus imprudently provoked the rapacious spirit of the Barbarians, soon discovered and lamented the difficulty of dismissing these formidable allies, after they had tasted the richness of the Roman soil. Regardless of the nice distinction of loyalty and rebellion, these undisciplined robbers treated as their natural enemies all the subjects of the empire, who possessed any property which they were desirous of acquiring Forty-five flourishing cities, Tongres, Cologne, Treves, Worms, Spires, Strasburgh, &c., besides a far greater number of towns and villages, were pillaged, and for the most part reduced to ashes. The Barbarians of Germany, still faithful to the maxims of their ancestors, abhorred the confinement of walls, to which they applied the odious names of prisons and sepulchres; and fixing their independent habitations on the banks of rivers, the Rhine, the Moselle, and the Meuse, they secured themselves against the danger of a surprise, by a rude and hasty fortification of large trees, which were felled and thrown across the roads. The Alemanni were established in the modern countries of Alsace and Lorraine; the Franks occupied the island of the Batavians, together with an extensive district of Brabant, which was then known by the appellation of Toxandria, and may deserve to be considered as the original seat of their Gallic monarchy. From the sources, to the mouth, of the Rhine, the conquests of the Germans extended above forty miles to the west of that river, over a country peopled by colonies of their own name and nation: and the scene of their devastations was three times more extensive than that of their conquests. At a still greater distance the open towns of Gaul were deserted, and the inhabitants of the fortified cities, who trusted to their strength and vigilance, were obliged to content themselves with such supplies of corn as they could raise on the vacant land within the enclosure of their walls. The diminished legions, destitute of pay and provisions, of arms and discipline, trembled at the approach, and even at the name, of the Barbarians.