Battle of Mursa Major

The Battle of Mursa Major was fought in AD 351 between the eastern Roman armies led by Constantius II and the western forces supporting the usurper Magnentius.

The battle took place in the valley south of the Drave river, near its confluence with the Danube, in modern-day Croatia.^[2]

Background

After Constantine I's death in A.D. 337 he was succeeded jointly by his three sons, Constantine II, Constantius II, and Constans, as well as two of his nephews, Hannibalianus and Dalmatius.^[3] The latter two were executed soon after by Constantius, either in the hope of acquiring their portion of the Empire, or impelled by the murderous jealousy of his advisers,^[4] and the empire was divided anew. Constantine took Gaul, Hispania, and Britain, while Constans acquired Africa, Italy, and Illyricum, and Constantius inherited Asia, Egypt, Thrace and the provinces of Greece and Macedonia.^[5]

Filled with resentment at what he considered an unfair division, Constantine attacked his brother Constans in 340, but was ambushed and killed near Aquilia in northern Italy. Constans took possession of the provinces of the west, and ruled for ten years over two thirds of the Roman world, a territory extending from the Atlas Mountains in the south to Hadrian's Wall in the north, and from the Strait of Gibraltar in the west to the pass of Suchi in the East.^[6] In the meantime, Constantius was engaged with a difficult war against the Persians under Shapur II in the east.^[7]

By A.D. 350, however, the pride and mismanagement of Constans had thoroughly alienated his subjects, and room was opened for the ambitions of Magnentius, a barbarian general in the service of the empire, and Marcellinus, the count of the largesse. In that year at Autun, Constans was deposed and shortly killed, and Magnentius had himself proclaimed Augustus of the west.^[8] In order to prevent Vetranio, Constans' lieutenant in Illiyricum, uniting with Constantius, Magnentius encouraged him to assume the purple and the rule of Illyricum in his own right, and the two jointly dictated their terms to Constantius II: if he granted their claims and confirmed their possession of the west, they would allow him the undisturbed mastery of the east. But should he dare to rise in vengeance of his brother, and plunge the empire into the calamities of a civil war, they might guarantee him his instant destruction.^[9]

Constantius reacted with a combination of resolution and prudence, declaring war on Magnentius, while offering peace to Vetranio, who was innocent of Constans' death.^[10] Vetranio responded favorably to Constantius' overtures, and the two met at Sardica, on the border of their respective territories, to combine their forces for the war against Magnentius. Constantius then revealed his true intentions, and contrived, by an eloquent oration delivered in front of the entire army, to win the sympathies of Vetranio's troops, who remembered the glories of Constantine I. Vetranio was dethroned by his fickle army, now repentant of their disloyalty to the house of Constantine, and was sent into exile in Asia-Minor by Constantius .^[11] Constantius then advanced west with his reinforced army to encounter the usurper Magnentius.

The battle

Magnentius, as soon as he received Constantius's rebuff, had begun his preparations for war, and by now had taken up his position in Pannonia. Constantius advanced to meet him, and the entire summer of 351 was spent in ineffectual maneuvering through the province, without a decisive action occurring. Magnentius indeed, confident in the power of his German auxiliaries, made his utmost efforts to force his enemy to battle, but his adversary invariably evaded him.^[12] Finally, after Magnentius had inflicted repeated minor reverses on the emperor and penned him up in the marshy north-eastern region of Pannonia, the latter was disposed to conclude peace, and sent his praetorian prefect, Flavius Philippus, to Magnentius's camp with offers of an accommodation. But by now Magnentius refused to come to terms, and contemptuosly dismissed the ambassadors. However this embassy was not without important results as Claudius Silvanus, a Frankish cavalry general on the side of the usurper, defected to Constantius on the secret persuasions of the prefect.^[12] At this point the usurper had laid siege to Mursa, a city on the south bank of the Drave with a famous bridge spanning the river. Constantius, reinforced, soon arrived to relieve the city, and in a sharp skirmish ejected the besiegers from an amphitheater outside the walls.^[12] The armies then drew up for battle on the plain south of the Drave, with the river on Constantius's right. Constantius had 80,000 men, and Magnentius 36,000.^[13] In the ensuing battle, which was one of the bloodiest of the century, the army of Magnentius was utterly overthrown. The heavy oriental cavalry on Constantius' left outflanked the enemies' right, and bent the Gallic lines back against the banks of the Drave, whence, operating in skillful concert with the army archers, they drove them after a great slaughter into the river. The usurper, having vindicated his personal courage in the fiercest combats of the day, was compelled to abandon the field of victory to Constantius, and fled to reform his defenses in Italy.^[14] His ally Count Marcellinus, instigator of the revolt, fought to the bitter end, his corpse thrown into the river at the end of the fight.^[15] The total losses of Magnentius were computed at 24,000 men, and Constantius's, due to the superior strength and stature of the Germans, even higher, at the number of 30,000 casualties.

Aftermath

Magnentius was soon forced, by the revolt of the province, to abandon Italy as well before the course of the victorious Constantius, though he turned in the retreat and won a minor victory at Pavia.^[16] After failing to secure peace from the emperor, he was compelled to contend with him again two years later at the Battle of Mons Seleucus, after extensive delays on Constantius' part. Magnentius was again defeated, and after receiving the intelligence that the Franks had crossed the Rhine at Constantius's instigation, and besieged his brother Decentius in Sens, the usurper flung himself upon his sword, bringing the three-year revolt to an end.^[15] A relentless persecution was then organized against all who were suspected of complicity in the revolt.^[17]

The religious significance of the outcome is not to be overlooked, since Magnentius was reputed to be favorable to paganism; Constantius' victory, which was supposedly heralded by a Cross in the sky over Jerusalem on the eve of battle of Mursa, secured the official establishment of Christianity as the religion of the Roman Empire.^[18] Also Constantius, during the fighting (at Mursa), had taken shelter in a tower adjoining the field with the Arian bishop of the province, Valens. The latter made certain to inform himself early on of the progress of the battle, and his strong assurances to Constantius that the contest had concluded in his victory, had a strong influence on the superstitious mind of the emperor, perhaps being responsible for the strong attachment to the Arian creed which he was to evince over the succeeding years.^[18]

References

• Langer, William L., (editor and compiler,) An Encyclopedia Of World History, (Houghton Mifflin Company Boston, 1952)
• Gibbon, Edward, The Decline And Fall of The Roman Empire, (The Modern Library, 1932)