With this monograph B. offers the first biography of Flavius Ardabur Aspar († 471 ce), a Roman politician and magister militum of Alan descent, the son of the magister militum Ardabur. He was a personality of particular significance to the developments in the East of the late fifth century, with important episodes in and outside Constantinople. He was not only a military commander, dealing with the Vandals and the Huns, but also a patricius, princeps senatus, consul and the most significant Eastern ‘maker of emperors’. This made him a key personality at the time of Marcian and Leo I, in the framework of whose acclamation he was a decisive supportive authority. Although Aspar clearly identified with the empire, he maintained his Arian creed, which was part of his gentile identity that distinguished him from most of the emperor's subjects and seemingly prevented him from accepting the imperial throne. Ultimately, his former protégé Leo I used this weakness to oppose Aspar by portraying himself as the champion of orthodoxy, a rivalry ending with Aspar and his son Ardabur being murdered at the emperor's instigation. This development ended the attempt of this military figure to gain the same control in the East as magistri militum like Aëtius or Ricimer had attained in the West.

Aspar is paradigmatic for the role of the gentile high military men in the Roman world of his time. B.'s monograph is composed of fourteen chapters, besides a list of illustrations, genealogical tables, a bibliography (with sources at pp. 210–12 and literature at pp. 213–24), an index and a preface. This is where readers learn about the unusual context in which the study emerged, which is not the result of a scholarly career but the felicitous product of genuine interest and scholarship of its author who, before his retirement, was a lawyer, who then used his time to write on the topic he had been reading about for decades. In so doing, he sought the exchange and advice of scholars from Georgetown University and the University of Ghent to improve the work. The result is a monograph that benchmarks against other academic works of the field, refreshingly proving that genuine interest paired with the ability and willingness to acquire the necessary methodological tools and skills may result in productive scholarly work. The subsequent chapters include a discussion of the historical significance of Aspar, his barbarian identity, the career of his father Ardaburius, followed by a study of Aspar's struggle against the Vandals in 431–435 and Attila's Huns until 450, after which the investigation turns towards Aspar's support of the emperors Marcian and Leo I, followed by his rivalry with the same and the future emperor Zeno, and Aspar's end.

Although Western military leaders have received much scholarly attention (T. Stickler, Aëtius [2002]; P. MacGeorge, Late Roman Warlords [2002]; T. Janßen, Stilicho [2004]; F. Anders, Flavius Ricimer [2010]; J.W.P. Wijnendaele, The Last of the Romans [2015]), this is not the case for their Eastern counterparts and their role in the inner-Roman struggles for power. B.'s work thus addresses an important desideratum of research. A particular merit of the study, given its unusual context, is that B. is not content with writing a biography of this key figure of late Roman history but skilfully manages to frame it in its global context and to address essential questions in accordance with scholarly practice. B. thus uses Aspar's path and its chronology to survey a particularly dynamic period of European history and its process towards what we call the Middle Ages; the result is a study also of the final phase of late antique emperorship in the East. It focuses on the period after the extinction of the Theodosian dynasty without a male heir, around 455, which ended the phase characterised by child emperors, when emperors were once again adults but required further legitimacy. This was initially done by seeking marriage alliances with the fading dynasty and the partnership and support of high military commanders like Aspar. The study does not consider the written evidence alone, but also discusses pictorial evidence from coins and the so-called Missorium of Ardabur Aspar of 434, showing Aspar and his son Ardabur, images included in the book.

The underlying question of the study is why Eastern emperorship survived, which is approached by looking at political transformations and their scholarly treatments, which regularly include comparisons with the West by stressing the similarities in structure. After a short discussion of the overall significance of the topic, B. takes on current discussions about identities and their potential adaptability to create a work that does not come with obsolete ideas but freshly picks up where research currently stands. B. stresses that it is not helpful to presume a dichotomy of barbarians and Romans when addressing individuals such as Aspar, a culturally assimilated native from Constantinople with important connections to both spheres, even if his Arian creed was perceived as a gentile marker and could make him vulnerable. Still, Aspar's Arian confession did not prevent many in Constantinople from offering him the status of emperor. In this and the subsequent case of his son Patricius, who became Caesar under Leo I, the imperial status of an Arian was only opposed by a strong clerical minority insisting on the emperor adhering to imperial orthodoxy. B. shows to what extent the outcome of the struggles between the emperor and high military commanders, as represented by Aspar, was not only dependent on the relevant institutional and personal structures but also on the personality of the protagonists and their respective families and supporters. As in the West, this included not insignificant armed followings, composed in Aspar's case of men of mainly Gothic descent, which helped individuals of comparable military rank gain the upper hand in the West. The Eastern emperor Leo I, whose relation to Aspar was initially clearly inferior to the latter, prevailed over his magister militum because he could outplay him on a personal level (pp. 203–7). This conflict thus was less a struggle between barbarians and Romans than a rivalry between two men with gradually opposing aims. The end of Aspar, in 471, ended any attempts of the Eastern military to control the imperial succession (p. 199). B.'s argument is important as it shifts answering the overall question about the survival of the East away from similarities in structure to the fortuitousness of individuals and their respective choices and abilities. This approach would also be worth adopting to discuss further the significance of individual characters and choices in the gradual weakening and subsequent fall of Western emperorship.

The main issue with the study, as noted in other reviews, is its virtual restriction to English-language scholarship, which is particularly relevant given the significant research available on the topic in German, including E.P. Glushanin's seminal Der Militäradel des frühen Byzanz (1991), with relevant treatments of Aspar, and Stickler's Aspar und die westlichen Heermeister (2015), which compared this case with that of the Western military. In view of that, this thoughtful study offers a most welcome basis, leaving some unpaved tracks for future work.