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This book presents a study of the reign of Constantius II, a son of Constantine I who ruled the Roman Empire for a total of thirty-seven years, first as Caesar (r. 324–337), and then as Augustus (r. 337–361). It is also a study of the reigns of his much less well-known brothers, the Augusti Constantine II and Constans. It is not, however, a biography of these figures in the traditional sense of that term for reasons discussed later in this introduction. The three brothers began their imperial careers as co-rulers of subordinate rank (as Caesars) with their father and became Augusti some months after his death in May 337. The controversial nature of Constantine’s emperorship was apparent even during his reign,1 and assessments proposing its divisiveness intensified in the years following his death.2 In this regard, Constantine’s historical impact was reflected in the reign of his nephew, the emperor Julian, who became sole Augustus (r. 361–363) following Constantius II’s death in November 361. Modern writers of historical narratives tend overwhelmingly to value those rulers from whose reigns clear themes or lessons can be wrought. As a result, encouragement is given to create dramatising narratives. With regard to Constantine, he is recalled as the emperor who promoted Christianity across the empire,3 while Julian is remembered as the emperor who sought to undermine his uncle’s religious revolution by promoting instead his own interpretation of the empire’s traditional cults.4 By contrast, the reigns of Constantine’s sons appear to offer no comparable “take-home message”. Instead, simplified judgements frequently attend efforts to recollect or characterise the principal features of their reigns: In the case of Constantius II, scholarly attention has traditionally focused on his involvement with the Christian Church which has tended to result in reductionist assessments of him as, for example, an “Arianizing emperor”,5 while ancient slanders about the sexuality and aptitude of Constans are commonly repeated with little or no critical comment,6 or in the case of Constantine II, little or nothing is said at all.7 Indeed, it is something of a historical irony that those individuals who at various times set themselves up as alternative rulers to the Constantinian emperors have garnered greater attention in recent years, with Magnentius, the general who rose in revolt against Constans in 350, representing the most heavily scrutinised of the period’s usurpers.8 Although this neglect of the Constantinian emperors is beginning to change (see below), new studies of Constantius II and the dynasty of Constantine I more broadly are urgently needed. It is the purpose of this study to analyse the principal themes and issues raised by the reigns of Constantine’s sons, inevitably with a focus on Constantius II as the longest serving of the Augusti from this period, and to synthesise historic and current trends in research on the period.
Appointed Caesar on 8 November 324,9 the day of the foundation of the city of Constantinople,10 Constantius II progressed to the position of Augustus along with his elder and younger brothers, Constantine II and Constans, on 9 September 337, following a bloody coup in the summer of that year which removed many high-profile individuals, including the reigning Caesar and the brothers’ cousin, Flavius Julius Dalmatius, in a move that represented an unqualified rejection of Constantine I’s arrangement for the future of the imperial college. Following the death of their father, the brothers divided the empire into three not wholly equal shares. Constantine II received the western territories (dioceses of Britanniae, Galliae, Viennensis, Hispaniae, along with the Alpes Cottiae); Constans took over the central territories (dioceses of Italia, Africa, Pannoniae and Moesia) and Constantius II controlled the eastern territories (the dioceses of Oriens, Asiana, Pontica and Thracia).11 This arrangement lasted only until April 340 when Constantine II and Constans came to blows in battle outside Aquileia, resulting in the death of Constantine II and the reallocation of his territory to Constans.12 While relations between Constantine’s surviving sons were never especially harmonious, a decade of relative stability followed during which attempts were made to create “pan-empire” solutions to a variety of issues, for example, resolving disputes between the factional Christian communities of the empire. A high-level coup led by senior members of both the army and the civil administration in the western empire ousted Constans in January 350 and in so doing threw the hold of the Constantinian dynasty over the empire into disarray. In order to assist in an increasingly disharmonious environment marked by foreign and now civil wars, Constantius appointed his cousin, Gallus, as Caesar on 15 March 351. However, only a year after the death of the usurper Flavius Magnus Magnentius in August 353 and the Constantinian recovery of the western empire, Gallus was executed on Constantius’ orders in October 354 following a series of catastrophes in the management of the east. Gallus’ half-brother, Julian, was Constantius’ next appointment on 6 November 355, seconded to the position of Caesar in order to assist Constantius in restoring Constantinian rule to the west, with Gaul a high priority. For a short period of time, Julian’s appointment led to several successes in a region scarred by recent events. However, a fissure that may already have existed between the two cousins following the assassinations of 337 opened more fully in light of a combination of internal (the preference of the Gallic troops for Julian over Constantius) and external factors (the continued challenge to Roman hegemony in Osrhoene and Mesopotamia by the Persian Empire), which resulted in Julian’s acclamation by his troops in the early months of the year 360. A new civil war between members of the Constantinian dynasty seemed on the cards, only to be avoided as a result of Constantius’ death on 3 November 361. The mantle of emperor passed to Julian whom Constantius had named as his successor just prior to his death, and the Constantinian legacy gained a minor extension to its existence in the brief reign of Julian, the nephew of Constantine I.
These are the broad-brush strokes of a period that lies between the reigns of Constantine I (r. 306–337) and Julian “the Apostate” (r. 361–363), two giants of posterity in the history of the fourth century. Bloody coups, sibling rivalry, usurpers, civil war, court intrigues and treason trials, belligerent bishops and barbarians hammering on Rome’s frontiers: Together, these represent the period’s traditional points of discussion. Yet, the broader context for the events of the reigns of Constantius and his brothers is frequently overlooked, or when it is analysed, it is done so in a fashion that consciously or unconsciously recapitulates the agenda-driven themes of ancient historiography and earlier scholarly interpretations. What follows then in the first section of this introduction is a brief overview of some of the defining features of the empire inherited by the sons of Constantine, and a survey of the impact of their reigns on both the short- and long-term conditions of the later Roman Empire. The post-Constantine period was characterised by the continuation and, in certain areas, the intensification of long-standing trends in the configuration of imperial authority both within and beyond the territorial limits of the Roman Empire. In the first instance, the sons’ reigns witnessed the continued relativisation of Rome’s military authority. Militarily speaking, it is certainly correct to say that the Roman Empire was “at bay”13 during this time. The ambitious ruler of the Sasanian Empire, Shapur II (r. 309–379), who had made a name for himself by aggressively subduing the tribes of the Arabian Peninsula during (c. 326) the reign of Constantine,14 intervened intermittently – and on occasions, decisively – in contested areas of Armenia and Mesopotamia throughout Constantius II’s imperial career, and prompted the emperor to adopt a three-pronged policy of “defensive strength, offensive power and diplomacy”15 in order to deal with Shapur’s ambitions. The reason for Shapur’s aggression is seemingly disclosed in a letter in his name to Constantius from 358,16 in which Shapur alludes to the treaty established between the two empires in the year following the defeat of the Shah Naresh (r. 293–303) by the Caesar Galerius in 298: “It is my duty to recover Armenia with Mesopotamia which double-dealing wrested from my grandfather [Naresh]”.17 While the authenticity of this exchange of imperial correspondence is moot,18 our source would appear to reflect Persian judgements about the punitive nature of the settlement established by the Romans at the end of the third century.19
The escalation of Persian aggression towards Armenia and the cities of north-eastern Mesopotamia during the final years (358–360) of Constantius’ reign illustrates the connected realities of imperial power at this point in the fourth century. For most of the 350s, Sasanian forces were pre-occupied with external threats of their own. Shapur’s efforts to subdue a confederacy of Iranian Huns20 intent on encroaching beyond the north-eastern frontier of Iran came at a tremen...
