In this doctoral dissertation of the University of Padua, Marco Rocco seeks to trace the institutional evolution of the Roman army from the Severans to the death of Theodosius I. Although hardly virgin territory, Rocco justifies the enquiry as an attempt to provide a comprehensive synthesis hitherto lacking, at least in Italian scholarship, with the objective of identifying interrelationships and clarifying causal links that might explain “gli elementi di persistenza e i momenti di cesura”. Certainly Rocco’s decision to couple the third and fourth centuries recognises a long-term desideratum which previous scholarship has not properly addressed, partly owing to conventional periodizations of Roman military history, whereby the third century often slips between specialisms.
A preface by Luigi Bessone justly commends the vast breadth of this study; indeed, the diversity of historical problems confronted by Rocco might have furnished sufficient material and challenge for a dozen doctoral theses. In five chronological sections (the Severans to 284; Diocletian and the Tetrarchy; Constantine; 337 to Adrianople; Theodosius I) Rocco treats some or all of the same interrelated themes: unit types, organisation and distribution; numbers of effectives; recruitment and “barbarisation”; command structures; frontier strategies; equipment and tactics; soldier-civilian relations, touching upon adjacent cultural and socio-economic spheres.
Chapter 1 begins with a lengthy discussion of the constitutio Antoniniana, in which Rocco discerns primarily military-fiscal motivations: increased revenues for the aerarium militare and regulation of citizenship as a recruitment qualification. He proceeds to examine early third-century institutional innovations, notably the creation of, in his view, the first permanent “mobile army” which, even if originally intended for internal security, became the nucleus of imperial expeditions from the reign of Caracalla, to which Rocco traces the designation sacer comitatus. He also investigates modifications to military careers, particularly praetorian prefects, and the protracted process whereby equestrian viri militares superseded the senatorial antiqua nobilitas in/by the reign of Gallienus.
Consideration of defensive strategies in the later third century accentuates the impact of political fragmentation on military deployment and the evolving role of the comitatus as a strategic strike force. Investigation of the terminology and structural typologies of defensive installations identifies innovations, typically regional in origin, some of which potentially inspired developments elsewhere or empire-wide. The creation of a system of “in depth” defence in the Gallic Empire exemplifies zonal particularity along the limites.
Discussion of the late third-century proliferation of new categories of cavalry unit, characteristically styled equites ( promoti, Dalmatae, stablesiani, scutati, Mauri, sagittarii), is disappointing, even accepting the difficulties of the evidence. While Rocco rightly discards Gallienus’ “cavalry reform” as a twentieth-century myth (134), his decision to examine the equites in a purely “geostrategic” context (87-9) overlooks the wider (if not necessarily long-term) significance of the expansion, reorganisation and heightened profile of cavalry in this period.
A section concerning combat appreciates changes to soldiers’ equipment and clothing, and contemporary representations thereof, and is sensitive to socio-cultural perspectives, but a cursory survey of tactical developments oversimplifies complex issues and presents contentious questions as if settled. Analysis of the distribution of legiones and auxilia and the total number of effectives at Diocletian’s accession involves customary number crunching, complicated by Rocco’s inference that recently created legiones were smaller and his conviction that Vegetius’ antiqua legio reflects late third-century realities. Nevertheless, the final picture of an army much the same size in 284 as in 235, despite the intervening “crisis”, is plausibly argued.
Chapter 2 begins by investigating the composition of Tetrarchic armies. Rocco emphasises the traditional framework of comitatus (pl.) amplified by ad hoc vexillationes and identifies regional differences (e.g. the western preponderance of new-style auxilia), although more perhaps could have been said on regionality as a defining characteristic of military developments during the Tetrarchy. Rocco traces the changing number, shape and location of legiones, notably fragmentation by permanent vexillatio, and elucidates terminological obscurities (e.g. lanciarii / lancearii). A lengthy discussion of new recruitment mechanisms and their fiscal consequences is instructive, even if the “normal” functioning of the system remains somewhat elusive, given that legislative sources, for which the Principate offers almost no comparanda, frequently respond to specific crises.
Rocco hypothesises that the drastic diminution of old-style auxilia ( alae, cohortes) witnessed in the Notitia Dignitatum, involving the disappearance of around four-fifths of such units documented under the Principate, compared to the doubling of the number (if not the manpower) of legiones under the Tetrarchy, can be explained by positing the conversion of auxilia into legiones, though without actually abolishing this class of auxilia. Rocco sees this “promotion” as a consequence of the equalisation of civic status by the constitutio Antoniniana and the long-term uniformisation of equipment and tactics. Such a large-scale reclassification of existing troops would obviate the traditional notion that Tetrarchic restructuring of the army entailed massive recruitment, a view some have already questioned. As Rocco provides no explicit evidence for auxilia -to- legio conversion, this hypothesis must rest on circumstantial convenience. His attempt to show, in turn, that the armed forces of the Tetrarchs were not significantly larger than those of preceding Soldatenkaiser, though by no means implausible, cannot escape the imponderables of such arithmetic. His papyrus-based calculation of a specimen comitatus (Galerius’ in 295) is more persuasive, at least as a general order of magnitude (25,000).
Following a discussion of fabricae and implications for equipment production, Rocco quickly surveys high commands (praetorian prefects, duces) before entering the minefield of late Roman regimental hierarchies. Here a tendency to rehearse the arguments of different scholars yields apparent inconsistencies, e.g. the officer- grade ducenarius cannot etymologically derive from both the equestrian ducena dignitas (235-6) and, as Vegetius supposes, a command of 200 legionarii (131, 229-30). Treatment of this complex subject would have benefited from greater precision in defining when a term signifies a rank, post or dignity, especially for designations with more than one meaning (e.g. again ducenarius, for which references are cited indiscriminately: 237). I am puzzled why a regimental hierarchy drawn from the late sixth-century Strategikon (but conflating ranks with posts and infantry with cavalry) is cited in relation to “coorti ausiliarie dioclezianee” (232).
The chapter concludes with a sector-by-sector reassessment of the evidence for a Diocletianic building program on the frontiers. Although cited bibliography occasionally seems dated (e.g. for Britannia), Rocco’s argues persuasively for a traditional linear (rather than “in depth”) defence designed to facilitate offensives.
Chapter 3 argues that, in contrast to Diocletian’s traditionalism, it was Constantine who created the late Roman army, which was essentially a product of his rise to power. Rocco catalogues the many campaigns of augusti / caesares against external enemies 306-337, which rarely share the historiographic limelight with internal power struggles and pagan-christian conflict. An excellent analysis of the evolution of different classes of troops – comitatenses, scholae palatinae, ripenses / riparienses, cohortes / alae – stresses status, remuneration and role in recent civil wars over tactical or strategic functions. Discussion of ripenses / riparienses is especially enlightening in relation to the later- attested category of limitanei.
An uneven section on troop-types is followed by more on army sizes, well-trodden ground, but conjecturing the temporary enlargement of armies for civil wars, analogous to the Late Republic. This potentially explains the high figures in some sources, notoriously Zosimus, and contextualises the spate of legislation on veterans’ privileges in 318-325, again with parallels to Octavian. A brief treatment of quartering soldiers, and to what extent comitatenses were “mobile”, recites the usual litany of abuses against civilian hosts in urban billets.
Discussion of “barbarisation”/“Germanisation” rejects attempts at proportional calculation, but infers substantial enlistment of barbarian/Germanic troops, starting under Constantine and escalating from the 350s-360s, in contrast to a trend in recent (especially anglophone) scholarship to minimise its significance. Offering more than a rehearsal of a traditional paradigm, Rocco examines the mechanisms of recruitment-integration, sensibly connecting enrolment of barbarians with long-term socio-cultural developments within the Roman empire and new fiscal apparatus of recruitment (principally aurum tironicum) from the Tetrarchy. He attempts to strike a balance between countervailing tendencies of “Romanisation” and “Germanisation”, allowing for reciprocal influences, but interpretation inevitably entails impressionistic judgements. It remains easier to trace the enlistment of non- Romans/Germani, arguably in large numbers, than to demonstrate the consequences, if any, for the operational practices and capabilities of Roman armies. Germanic influences surveyed by Rocco are chiefly in the sphere of “military culture” (dress, emblems, ceremony) and even here the evidence is often more complex than presented, especially against a background of centuries of Roman military eclecticism.
Examination of high commands, notably praetorian prefects, magistri ( militum / officiorum), comites and duces, emphasises shifting terminology, functions and status. There follows a sequence of themes relating to frontier security: a conventional summary of the intensification of “guerriglia”, seen as “una vera rivoluzione” (368), though both the theory and practice have a longer pedigree and Rocco risks generalising an opponent-specific development; an all-too-brief section on the provisioning of garrisons, which may point the way for future research; and a survey of Constantinian fortifications, demonstrating continuing offensive potential.
Chapter 4 summarises military operations 337-378, with remarks on the evolution of magistri militum, followed by analysis of units created in this period and the formalisation of orders of precedence and/or modes of deployment of different classes of troops, including limitanei, pseudocomitatenses, palatini. Rocco (as previously RSA 2009) re-evaluates evidence for the regimental appellations seniores / iuniores, arguing that these distinctions do not signify unit seniority, as recent scholarship holds, but relate, at least in origin, to age groups of servicemen, possibly reflected in different operational and/or tactical duties.
An intelligent investigation of interrelated developments in manpower and finance, and their consequences for recruitment and “barbarisation”, drifts into a superficial review of technological exchange between the empire and barbaricum. A somewhat unfocused section includes methods of assimilating non-Romans; a wide-ranging enquiry into soldier-civilian relations; and perusal of the Abinnaeus archive. There follows another survey of building initiatives on the frontiers, principally European. The chapter concludes with a glance at the performance of cavalry and infantry in selected engagements, which preludes a brief, largely Vegetius-inspired consideration of weaponry and tactics.
A fifth, epilogic section, covering events 378-395, examines how Theodosius restored order in the Balkans after Adrianople, including the evidence for agreements with different groupings of “Goths” and their consequent status and terms of service as “ foederati ”. Rocco also considers Theodosius’ two interventions against western usurpers; the proliferation of eastern magistri militum; and new units documented in the East, whether newly created or possibly transferred from the West, potentially contributing to its subsequent chronic weakness. Finally, he rehearses the arguments surrounding Vegetius’ much-discussed allegation of the abandonment of armour under Gratian.
A “riepilogo tematico” offers a diachronic reprise of the various lines of argument concerning “persistenze” and “cesure”. Rocco identifies structural, operational and cultural continuities in the evolutionary dynamics of the late Roman army, much of which he traces to Severan origins or precedents, and overarching consistencies in the objectives and functioning of imperial defensive strategy. He distinguishes Constantine as the only major military innovator in this period, though even here one might have discerned systematisation of preceding ad hoc and/or regional measures. Rocco’s appraisal of significant discontinuities includes Tetrarchic innovations in recruitment; new modes of armament production in state manufactories; Constantine’s reform of high commands and their subsequent “barbarisation”; urban hospitium of comitatenses and its implications for soldier- civilian relations; the post-Adrianople accommodation of “Gothic” foederati. A thoughtful appendix (published RSA 2011) considers perceptions of barbarian ethnic identity.
On the whole, this well-researched book succeeds in synthesizing multiple complex themes, developments and controversies. Given its scope and sources, so bedevilled with uncertainties, it would be no surprise if the text evokes myriad disagreements and alternative interpretations on points of detail and general principles, but Rocco’s analysis is typically sensible, well argued and overall free of kite flying, bandwagon jumping and for-its-own-sake revisionism. Its strengths include rigorous application of chronology, sensitive Quellenforschung and attention to regional particularities, thereby avoiding generalisations and anachronisms on the basis of deficient evidence, while affording a clear presentation of the course and pace of developments. Rocco’s approach excels at an institutional level (composition of armies, unit histories, classes and categories of troops, command structures), which provides the main narrative thread, and he is adept at interweaving the intricacies of manpower, recruitment and finance. His treatment of operational aspects, including tactics and logistics, is less successful, while some of the excurses on numerous other topics, often cursory, uneven and/or derivative, could have been pruned or developed elsewhere. Errors are very few and minor.1 Misprints are negligible.
Miscellaneous cavils should not detract from my favourable evaluation of the book as a whole. One suspects that it will become primarily a digest of scholarship and point of reference for Italian readers, but one can hope that it acquires a wider audience.
1. E.g. 51: evidence cited for continuity of the old-style numerus ( Herulorum) in fact relates to an auxilium palatinum ( Heruli seniores); 326: confuses Lactantius Placidus with more-famous homonym; 344: Calocerus rebelled in Cyprus not Crete; 459: the legionary grades augustalis, flavialis are not “altrimenti sconosciuti”, but well attested papyrologically.