This massive volume began as a dissertation at the Norwegian University of Science and Technology, while the author also credits the earlier inspirational influence of Bernard Bachrach at Minnesota. Petersen indicates (p. 1) that his aim is “to examine the organization and practice of siege warfare among the major successor states of the former Roman empire”. These include the Byzantine Empire, the Ostrogoths, Visigoths, Lombards and Franks, and “conquest” states, particularly the early Islamic Caliphate. The author argues for continuity of late Roman siegecraft into the successor states with their resulting ability to conduct sophisticated offensive and defensive siege operations. Notably Petersen characterizes siege warfare as “one of the most difficult and resource-intensive forms of warfare”, citing its demands for logistics, engineering knowledge, training, planning and manpower (p. 256).
In the introduction Petersen indicates that he follows Sarris in using the concept of widespread bipartite estate management among great land owners, and Goffart for the continuation of Roman techniques to extract labour, military service and wealth, in the successor states. He also employs Geertz's concept of “thick description” to provide context for the often brief comments on sieges in the sources.
Chapters 1–4 consider the organization of siege warfare and its place in the respective successor/conquest states, beginning with the transition from late Rome. The initial discussion of Byzantium serves as the touchstone for analysis of Ostrogothic, Visigothic, Lombard and Frankish methods. Chapters 5–6 argue for shared approaches in these societies before, during and following sieges, while chapters 7–8 and three appendices investigate technological diffusion to these societies as well to conquest states. In chapter 1 the author contends that the predominant view that military infrastructure disappeared in the West with the demise of Rome is incorrect, that as in the East, private military forces, supported by landed estates, continued to preserve administrative and logistical capabilities which are evidenced in a dozen sieges in the successor states in the West in the first wars of the sixth century and which became regularized in those states. Petersen suggests that isolated approaches to the study of individual components of the Western institutional framework have led to this misunderstanding. In chapter 2 the author notes the survival of the Byzantine army as a centralized institution, but observes that it was often supplemented by other institutions and groups, including local defence forces involving bishops, landowners and civilian craftsmen. He argues that these East Roman practices influenced those in the West through wars, client relations and acculturation. In chapter 3 the author contends that Ostrogoths, Visigoths and Lombards resembled in their armies, respectively: (a) traditional Roman forms; (b) the Roman military organization of the fifth century; and (c) the Byzantine forms; and served as intermediaries of Roman influence to the Franks. In chapter 4 Petersen (“in stark contrast to the views of most historians”) asserts the basic similarity of Frankish armies of the mid-sixth century to those of Justinian, and of the seventh century as strongly influenced by mid- to late sixth-century practices of Roman Italy, by various East Roman practices, and by the Visigoth model.
The next two chapters examine “the anatomy of a siege”, initially tactics and technology, and then economy, society and culture. Chapter 5 includes detailed discussions of offensive siege methods, including archery and ladders, artillery, camps and encircling fortifications, mounds and towers, wallbreaking machines and engineering, then considers defensive responses, including various items thrown from the walls against besiegers, sorties, and relieving armies. The chapter concludes with a “thick description” of sieges of the period to refute characterizations of them as basic and simple, arguing instead for their complexity and sophistication. Chapter 6 surveys issues of defensive infrastructure and fortification, the symbiotic relationship between city and countryside, morale, politics, and consequences of survival or capitulation.
Chapter 7 examines transmission of technological knowledge and poliorcetics, focused particularly on groups external to the late Roman tradition, e.g. Slavs, Avars and Arabs. Petersen concludes that the Arabs “excelled in siege warfare as early as 640 at the latest” and by the 650s “were mobilizing greater resources than Romans or Persians” (p. 389). The appropriation of Roman (and Persian) methods originated in their respective Ghassanid and Lakhmid Arab client relationships and is evidenced, among others, by Arab assaults on the walls of Dvin in 640 using an archery, ladder and smoke approach and on Caesarea using “massed artillery along with ladders” (p. 391). Persian defectors also played a role. These arguments are supplemented by detailed appendices which describe and analyse “The Arab invasion of Palestine and Syria”, “ʿIyad ibn-Ghanm's invasion of Armenia in 640” and “Arab grand strategy, 663–669”.
Chapter 8 examines the diffusion of the traction trebuchet and how some successor states successfully appropriated and domesticated this technology. Petersen argues that previous work on the device has been technical-philological, to the neglect of social context and diffusion mechanisms. He suggests a much earlier date than the current consensus (c. 580) for its appearance in the eastern Mediterranean, namely “at the latest around 500” or “even ... around 400” (p. 421) based on his analysis of passages in Joshua the Stylite (on the siege of Amida, 502), and others in Procopius (Petra, 550) and Agathias (Onoguris 555). He does not engage with earlier scholars who have seen the stone thrower at Amida as an onager, and his interpretation of Procopius' “wooden tower” as a trebuchet is debatable. Likewise while he is correct in asserting that the trebuchet serves as a benchmark for tracing subsequent technological diffusion, the related assertion that it required “similar resources and infrastructural support to maintain” as its predecessor (i.e. the onager) might be questioned. The lengthy “Corpus Obsidionum (Catalog of Sieges)” covers pages 457–764 and lists sieges chronologically by the name of the city/fort, the date, with source, secondary literature, and translations, original quotations and/or summaries.
The volume is a major achievement and the author deploys his arguments with a wealth of supporting detail. The “Corpus Obsidionum” will prove a very valuable resource. The assertion of continuity from late Rome to the early middle ages will, however, perhaps not find universal agreement.
