Flavius Julius Constantius, second son of Constantine I and Fausta, was born on 7 August 317 in Illyricum. He seems to have been made a Caesar on 13 November 324 in Nicomedeia. He was sent to Gaul when his brother Constantine II fought on the Danube in 332. At the time of his father’s Tricennalia he went to Constantinople and married his first wife, the daughter of his uncle Julius Constantius. When his father died in May 337, Constantius, who was campaigning in the east, rushed back to Constantinople and arranged for his father’s obsequies. He may have been the force behind the murder of a large number of relatives and retainers in a purge. The only male family members who survived were Julian and his half-brother Gallus. The purge may have had its roots in the religious squabbling between the Orthodox and Arian factions in Constantinople.[] In the first part of September 337 Constantius II and his two brothers met in Pannonia where they were acclaimed Augusti by the army to divide up the empire among themselves. The realm of Constantius II included the east, except for Thrace, Achaea, and Macedon. After his brother Constans I was killed by the forces of Magnentius in 350, Constantius obtained possession of his brother’s realm which included the territory of Constantine II, who had died in 340.[]
Constantius spent a great deal of his reign on military campaigns; between 337 and 350, he resided in Antioch, between 351-359 he spent much of his time in Sirmium and Mediolanum (Milan), and in 360-361 he lived in Antioch again. While in the east, he spent several of his summers campaigning against the Persians.[] Although he appears to have been a competent general, some contemporaries felt that Constantius was a better soldier in civil wars than in foreign combat and some disparaged his apparent reluctance to face the Persians. [] However, this judgement may be a bit unfair. Perhaps “mixed success” might be a safer description of Constantius’ military career. He succeeded in stopping every major Persian invasion, as the Battle of Singara in 348, costly to both sides, demonstrates. Indeed, when viewed in contrast with those of his immediate successors, Constantius’ struggles with the Persians appear in a more favorable light.
The Persians were not the only threat to the empire during his reign. Constantius also fought several campaigns against various barbarian groups. However, his greatest threat came from a series of usurpers who arose in various sections of the western portions of the empire. To cope with them, Constantius shifted his base of operations from the east to Mediolanum (Milan) during the 350s. Although the revolts of his kinsman Nepotian in 350 and that of Silvanus in 355 were repressed by his opponents or by the emperor himself, the usurpation of Magnentius and that of Vetranio formed the basis of a more serious threat to the foundation of Constantius’ rule. Both usurpers raised their standards in revolt in 350. Although Vetranio was repressed by Constantius into honorable retirement in the same year, it was only after the costly Battle of Mursa in 351 and the victory at Mons Seleuci in 353 that Constantius was able to quell Magnentius, who committed suicide in August 353.[] In order to keep the Persians in check while he was dealing with the various usurpers, Constantius had appointed his cousin Gallus Caesar in 351 and had sent him east to maintain a Roman presence there. Gallus, however, under the influence of his wife Constantina, soon challenged his cousin’s authority and was put to death by Constantius at the end of 354.[]
His first wife, the daughter of Julius Constantius, must have died in the ’40s or early ’50s because he married his second wifeEusebia in 353. Although the marriage was harmonious, she passed away in 360.[] Largely due to the influence of Eusebia, Constantius appointed Gallus’ half-brother Julian as his Caesar and dispatched him to Gaul in 355, while he went east to face the Persians. When Julian’s military successes between 355 and 360 became too much for Constantius to endure, he attempted to weaken the Caesar by asking that some of the Gallic troops be sent to him for service in the east. Julian’s troops acclaimed the Caesar as Augustus during January or February of 360; while en route to put down Julian, Constantius passed away at Mopsucrenae in Cilicia on 3 November 361. To give Constantius some credit, he is reported to have named Julian as his successor to avoid a succession crisis. At some point in 361 before his death he had married Faustina, who bore him a daughter, Constantia, posthumously.[]
Our chief source for Constantius’ reign is the great historian Ammianus Marcellinus.[] He presents a mixed view of that emperor. In some ways a sound administrator and competent general, Constantius is also portrayed as easily influenced by those around him such as his wives, courtiers and the eunuchs of the court (Ammianus 21. 16. 16). Ammianus (21.16.18) also attacks Constantius’ great interest in Church affairs–alleging that he bankrupted the courier service with calls for Church councils. Of course, imperial interest in Church affairs was a major policy of his father Constantine and it may be that Constantius was trying to emulate his model (if only with mixed success). Indeed, Constantius II (like his brothers Constantine II and Constans) was raised a Christian. Among his many laws is the famous CTh 16.10.2 of 341 which either prohibited or re-issued his father’s prohibition of pagan sacrifices. Sympathetic to Arianism, he spent a great deal of his reign calling Church councils. One of the longest-reigned emperors in Roman history, Constantius is hard for the modern historian to fully understand both due to his own actions and due to the interests of the authors of primary sources for his reign.[]
Barnes, T.D, Athanasius and Constantius: Theology and Politics in the Constantinian Empire. Cambridge, 1993.
________. New Empire of Diocletian and Constantine. Cambridge, 1981.
Blockley, R.C. “Constantius Gallus and Julian as Caesars of Constantius II.” Latomus 21 (1972): 433ff.
DiMaio, Michael. “The Antiochene Connection: Zonaras, Ammianus Marcellinus, and John of Antioch on the Reigns of the Emperors Constantius II and Julian.” Byzantion 50 (1980): 158ff.
________. and Duane W.-H.Arnold. “Per Vim, Per Caedem, Per Bellum: A Study of Murder and Ecclesiastical Politics in the Year 337 A.D..” Byzantion, 62 (1992): 158ff.
________. “Smoke in the Wind: Zonaras’ Use of Philostorgius, Zosimus, John of Antioch, and John of Rhodes in his Narrative on the Neo-Flavian Emperors.” Byzantion 58 (1988): 230ff.
________. Zonaras’ Account of the Neo-Flavian Emperors, (Ph.D. diss., University of Missouri-Columbia, 1977).
________. “Zonaras, Julian, and Philostorgios on the Death of Constantine I.” GOTR 36 (1981): 118ff.
Ensslin, Wm. “Magnentius (1),” RE 14: col. 445ff.
Frakes, Robert. “Cross-References to the Lost Books of Ammianus Marcellinus.” Phoenix 49 (1995): 232-246.
________. “Ammianus Marcellinus and Zonaras on a Late Roman Assassination.” Historia 46 (1997): 121-128.
Jones, A.H.M., J.R. Martindale, and J. Morris. “Eusebia,” the Prosopography of the Later Roman Empire, Cambridge, 1971, 1.300ff.
________. J.R. Martindale, and J. Morris. “Faustina,” PRLE. 1.326.
________. J.R. Martindale, and J. Morris. “Fl. Iul. Constantius 8,” PRLE. 1.226.
Kienast, Dietmar. Römische Kaisertabelle: Grundzüge einer Römischen Kaiserchronologie. Darmstadt, 1990.
Klein, R. Constantius II und die Christliche Kirche Darmstadt, 1977.
Leedom, Joe W. “Constantius II: Three Revisions,” Byzantion 48 (1978): 133-136.
Lucien-Brun, X. “Constance II et le massacre des princes,” Bulletin de l’Association Guillaume Budé ser. 4 (1973): 585-602.
Müller-Seidel, Ilse. “Die Usurpation Julians des Abtrünnigen im Lichte seiner Germanenpolitik.” HZ 180 (1955): 225ff.
Seeck, O. “Constantius (4).” RE 4: col. 1044ff
________. “Vetranio (1).” RE 8.2: col. 1838ff
[]Constantius II’s full name: ILS, 705, 724, 731-33, 737, 739, 8808; such variations as Flavius Constantius (Ibid., 730, 734) or Constantius (Ibid., 708, 710, 729, 736, 738, 740) appear on inscriptions.
For a listing of the sources that treat the parentage of Constantius II, see T.D. Barnes, New Empire of Diocletian and Constantine, (Cambridge, 1981), 45, A.H.M. Jones, J.R. Martindale, and J. Morris, The Prosopography of the Later Roman Empire, (Cambridge, 1971), s.v. “Fl Iul. Constantius 8,” 1.226-227, Michael DiMaio, Zonaras’ Account of the Neo-Flavian Emperors: A Commentary, (Ph.D diss., University of Missouri-Columbia, 1977), 281, n.18.
Although Barnes (New Empire, 85) and the authors of the PLRE (1.226) date the Caesarship to 8 November 324 based on literary evidence, epigraphic evidence (AE, 1937, #119: DiMaio, Zonaras, 360, n.14), more immediate than the literary evidence, presents a date of 13 November 324.
For Constantius’ early military commands and first marriage: Ibid., 359-60.
For a discussion of Constantius’ role in Constantine’s funeral, see idem., “Zonaras, Julian, and Philostorgios on the Death of Constantine I,” GOTR, 26 (1981) 118ff.
For a discussion of the purge of 337 and the sources that treat these matters, see X. Lucien-Brun, “Constance II et le massacre des princes,” Bulletin de l’Association Guillaume Budé ser. 4 (1973): 585-602; Joe W. Leedom, “Constantius II: Three Revisions,” Byzantion 48 (1978): 132-145, and Michael DiMaio and Duane Arnold, “Per Vim, Per Caedem, Per Bellum: A Study of Murder and Ecclesiastical Politics in the Year 337 A.D.,” Byzantion, 62(1992), 158ff.
[]For a discussion of the succession of the sons of Constantine to the imperial throne, see ibid., 198ff; for a listing of the sources which discuss the apportionment of the empire among the sons of Constantine and problems with their interpretation, see Michael DiMaio, “Smoke in the Wind: Zonaras’ Use of Philostorgius, Zosimus, John of Antioch, and John of Rhodes in his Narrative on the Neo-Flavian Emperors,” Byzantion, 58 (1988), 336ff.
[]For a complete listing of Constantius’ residences during his reign, his movements, and the sources that treat them, see Barnes (New Empire, 85ff; Athanasius and Constantius, 218ff); Kienast does much the same thing in briefer compass (Dietmar Kienast, Römische Kaisertabelle, [Darmstadt, 1990], 309ff); Seeck’s treatment of Constantius’ reign remains the classic (O. Seeck, RE 4, s.v. “Constantius (4),” col. 1044ff, although Barnes’ Athanasius and Constantius may soon supplant it.
For a reconstruction of the Battle of Mursa and the sources that treat it, see DiMaio, Byzantion, 58 (1988), 245ff.
[]For a discussion of Gallus’ fall from grace and the sources that treat the event, see ibid, 232ff, and idem., “The Antiochene Connection: Zonaras, Ammianus Marcellinus, and John of Antioch on the Reigns of the Emperors Constantius II and Julian,” Byzantion, 50 (1980), 170ff. See also R. N. Mooney, “Gallus Caesar’s Last Journey,” Classical Philology 53 (1958): 175-177. For a disputed plot of the usurper Magnentius to kill Gallus, see Robert Frakes, “Ammianus Marcellinus and Zonaras on a Late Roman Assassination plot,” Historia 46 (1997): 121-128.
[]For a discussion of the rise of Julian and the events leading up to the death of Constantius, see R.C. Blockley, “Constantius Gallus and Julian as Caesars of Constantius II,” Latomus, 21 (1972), 445ff; Ilse Müller-Seidel, “Die Usurpation Julians des Abtrünnigen im Lichte seiner Germanenpolitik,” HZ, 180 (1955). 227ff; and DiMaio, Zonaras, 329ff.
For a listing of sources on Faustina, see A.H.M. Jones, J.R. Martindale, and J. Morris, PLRE, s.v. “Faustina” 1.326.
[]Extant Books XIV through XXI of Ammianus’ Res Gestae treat the reign of Constantius. At least his lost Book XIII did also; see further, Robert Frakes, “Cross-References to the Lost Books of Ammianus Marcellinus,” Phoenix 49 (1995): 232-246.
Barnes’ Athanasius and Constantius is the locus classicus for any discussion of Constantius’ involvement with the Christian faith.