Very rarely has the figure of Constantius II (AD 317–361; Caesar 324, Augustus 337) attracted sustained scholarly attention. The causes for this inattention may be discerned in the historiographical tradition established in the latter half of the fourth century, which was almost uniformly hostile to the memory of the longest reigning and most successful of the sons of Constantine the Great. By virtue of his opposition to the traditional cults and his favouring a homoean creed in Christian worship, Constantius II has long been condemned to oblivion. Rooted in a close reading of the literary sources and drawing upon recent epigraphic discoveries and numismatic evidence, the monograph of Muriel Moser constitutes a welcome addition to the growing body of recent scholarship dealing with this important figure in the transition of Late Antiquity. Proclaimed Caesar on the same day that his father re-founded Byzantium as Constantinople (8 November 324), Constantius II stands at the cusp of the Middle Ages, the creator of more than one institution that was to endure for over a millennium.
In seven dense chapters, Moser reviews the prosopographical evidence for the involvement of senators in the administration of the Roman empire in the East between Constantine’s final victory over Licinius in late AD 324 and the death of Constantius II late in AD 361. With the two chapters of Part I (“A Unified Roman Empire (AD 312–337)”, pp. 11–82), Moser argues for the restored unity of the Empire after Constantine’s victory over Licinius in AD 324 and illustrates the reliance of Constantine upon local elites serving in the imperial administration as viri perfectissimi. With the next two chapters, which constitute Part II (“Ruling the East (AD 337-350)”, pp. 83–168), Moser argues for continuity under the sons of Constantine, notwithstanding their differences over dogma and such contentious figures as Athanasius of Alexandria. With the final three chapters of Part III (“Ruler of Rome and Constantinople (AD 350–361)”, pp. 169–312), Moser illustrates the process whereby Constantius II established the Senate of Constantinople and accorded it equal status with that of Rome.
This monograph calls into question a number of ideas (e.g. the creation of a Senate of Constantinople by Constantine and Constantius II’s reliance upon that Senate) that are standard in the modern scholarship. She establishes the reliance of Constantine and Constantius II upon members of the Senate of Rome for the government of the area stretching from Thrace through Anatolia and Syria to Egypt in AD 324–361. She likewise demonstrates persuasively that there was no Senate of Constantinople until Constantius II called it into being, an event that is suggestively linked to the struggle against Magnentius in the civil war of AD 350–353 (p. 217). Indeed, she illustrates how senators from western provinces were limited to administrative positions in the West and eastern senators to the East after the conclusion of that conflict in AD 353. What emerges is something akin to witnessing the mitosis of a cellular organism. The resolution of tensions between Old Rome and New Rome is accordingly revealed to have been one of the chief aims of the visit of Constantius II to Rome on the twentieth anniversary of his father’s death, an anniversary which seems to have been treated as though it marked the completion of twenty years of rule as an emperor with full powers (Augustus).
One of the virtues of this admirable treatment of technically complicated and seemingly unrewarding material is the detailed attention that Moser brings to the literary, numismatic, epigraphic, and legal evidence in her attempt to reconstruct individual careers and imperial policies. Attentive to the nuances of language, she brilliantly corrects standard translations of the term diasēmotatos, which was used by Eusebius of Caesarea (V. Const. 4.1.1-2) to indicate that Constantine co-opted large numbers of the civic elite of the East as viri perfectissimi (pp. 48–51). Alert to the contribution that coins may make, she buttresses this philological argument by the citation of a gold medallion with the obverse legend EQVIS (sic) ROMANVS, which was struck at Nicomedia in AD 325–326 and valued at 1.5 solidi (p. 51, fig. 2.1). Drawing upon an unpublished inscription on the base of a statue set up to commemorate the praetorian prefect Flavius Philippus in the city of Perge (thanks to the generous permission of Dennis Feissel), she establishes that the members of the Senate of Constantinople were addressed as “conscript fathers” by late AD 351 or early AD 352, and that this praetorian prefect established his residence at Constantinople as part of the war effort against Magnentius (pp. 189–196). Utilising yet other epigraphic evidence, she makes a strong case that Philippus survived imprisonment by Magnentius only to die in disgrace as one of the victims of the treason trials that followed the definitive victory of Constantius II (pp. 197–207). In like fashion, Moser deploys to good advantage legal texts such as a letter of Constantius II addressed to the Senate of Constantinople from Sirmium on 22 May AD 359 (CTh 6.1.15, trans. Project Volterra), which illustrates the procedural complications that accompanied the formation of a new senate in the East that was to all purposes the twin of its peer in the West.
This is a monograph that makes an excellent contribution to the field and will surely stimulate further work on Constantius II and the seminal transformations that occurred during the reign of an emperor who has too long been left in oblivion. Readers who are not adepts of prosopography may find some of the detailed discussions heavy going, and occasionally there are some bad slips. Moreover, various ideas (e.g. the association of the Victoria Senati (sic) with the vicennalia of Constantine in AD 326 and the interpretation of FEL TEMP REPARATIO coinage of AD 346/7 as referring to the 1100th birthday of Rome) fail to convince, and the author’s voice often seems still that of a student writing a dissertation. However, these are minor peccadillos. Overall, the contribution is solid and useful. Moser has produced a monograph that is a pleasure to read and offers a number of noteworthy and persuasive attempts to revise and delineate our vision of Constantius II and the participation of the elite in the government of the Roman empire at mid-century.
 There exist only two biographies exclusively dedicated to Constantius II: Pedro Barceló, Constantius II. und seine Zeit. Die Anfänge des Staatskirchentums, Stuttgart 2004; Sonia Laconi, Costanzo II. Ritratto di un imperatore eretico, Roma 2004. Now, however, there is also a work dedicated Constantius II and his brothers Constantine II and Constans and covering the period AD 337–361 in great detail: Pierre Maraval, Les fils de Constantin, Paris 2013.
 Naturally, there are exceptions, with some noteworthy monographs focussing upon a single aspect or another individual: Richard Klein, Constantius II. und die christliche Kirche, Darmstadt 1977; Chantal Vogler, Constance II et l’administration impériale, Strasbourg 1979; Hanns Christof Brennecke, Hilarius von Poitiers und die Bischofsopposition gegen Konstantius II. Untersuchungen zur dritten Phase des arianischen Streites (337–361), Berlin 1984; Studien zur Geschichte der Homöer. Der Osten bis zur Ende des homöischen Reichskirche, Tübingen 1988; Timothy D. Barnes, Athanasius and Constantius. Theology and Politics in the Constantinian Empire, Cambridge, Mass. 1993.
 Other works of note include: Gavin Kelly, Ammianus Marcellinus. The Allusive Historian, Cambridge 2008; Richard Flower, Emperors and Bishops in Late Roman Invective, Cambridge 2013; Johannes Wienand (ed.), Contested Monarchy. Integrating the Roman Empire in the Fourth Century AD, Oxford 2015; Adrastos Omissi, Emperors and Usurpers in the Later Roman Empire. Civil War, Panegyric, and the Construction of Legitimacy, Oxford 2018.
 E.g. confusion between homonymous father (praefectus praetorio Galliarum, cos. 331) and son (praefectus urbi Romae 359) when she writes “the consul (sic) Junius Bassus was buried” at the basilica of St Peter in the Vatican (p. 296, n. 88) and the assertion in the following note that 240 solidi is a “modest” figure in terms of revenue. To put the figure of 240 solidi into perspective, it should be remarked that if 3 solidi seem to have the purchasing power of € 15.000 in today’s world, then 240 solidi would translate as € 1.200.000. That seems a little less than modest.