In the mid eighth century, the Frankish Empire and the Islamic Caliphate both experienced a dynastic change (or ‘usurpation’) within the space of two years: the Carolingians replaced the Merovingian dynasty and the Abbasids replaced the Umayyad dynasty. Drews takes this historical coincidence as a starting point and a prism for studying Carolingian and Abbasid strategies of legitimization and for reflecting upon the room for manoeuvre of medieval political actors in these two empires. The author adopts a comparative approach, but throughout his study avoids blurring this approach with a cross-cultural history of interdependencies, influences, contacts, and the like. In this sense, he searches out commonalities, parallel processes, and differences without assuming that these entail reciprocal influences. The explicit aim of discussing and comparing the two dynastic changes is to get beyond the Eurocentric outlook of medieval studies and to integrate other cultural spheres into historiographical practice, in order to apply global historical approaches to the medieval period.

Drews discusses the dynasties’ strategies of legitimization in four main chapters, which discuss respectively: arguments used to legitimize the usurpation; practices of legitimization via the formation and use of elites; practices of legitimization with regard to the regal right to set norms; and cultural and religious parameters that set the framework for the different strategies. This discussion is framed with a heuristic application of the approaches of Max Weber and Pierre Bourdieu. The concepts of charisma and cultural capital are recurring themes in the discussion.

In his first main chapter, Drews shows that the Carolingians relied mostly on ritualistic and institutional forms of legitimization; that is, they claimed their legitimacy to rule by performing specific rituals such as anointing, and by referring to institutions such as the papacy. The Abbasids, in contrast, relied on a strategy of legitimization that focused on descent from the Prophet Muammad and the transmission of a hereditary charisma. One might disagree with the author that the Carolingian strategy was more advantageous because it excluded potential rivals who, in the Abbasid case, could lay claim to a similar descent and the same legitimacy. It is doubtful whether this led inevitably to ‘instability’ (p. 172), considering that the Abbasid dynasty survived some five centuries and that political rivals were hardly ever able to challenge their position as caliphs (whatever this office may have meant in practice). The possibility of raising similar claims to legitimacy was limited to a rather narrow, mostly Shiite, section within Abbasid society, and there is no indication that the Abbasids’ loss of effective power was in any way linked to such claims.

In the following chapter, Drews reflects upon on the formation of a consensus within the respective elites, as part of strategies of legitimization. The two dynasties had fundamentally different ways of recruiting elites. For instance, the Abbasids relied on mercenaries for staffing their armies, while the Carolingians had recourse to the indigenous aristocracy. On the other hand, the Abbasids had hardly any influence on the recruitment and formation of the scholarly elite, which was identical with the religious elite. The author’s contention is that this led, in the case of the Abbasids, to an imbalance between centre and periphery, as well as between differentiation and integration of the elites. Again, this is not entirely convincing. As it stands, the argument relies to some degree on a deficit hypothesis: that the absence of a certain set of practices (in this case the Carolingian) is by itself assumed to be problematic.

The third main chapter considers the central theological discussions of the period. In Western Christianity, the main one concerned the filioque clause in the creed – that the Holy Spirit proceeds from the Son as well as the Father. In the Islamic lands, it was the question of the createdness of the Qur’an. This highlights the difference between the religious policies of Charlemagne and al-Ma’mūn. After the caliphate had to withdraw from its attempt to impose its authority in the religious field, the dogma of the createdness of the Qur’an had to be dropped as well. This led ultimately to the loss of any independent caliphal authority in the fields of law and belief. Charlemagne, in contrast, was able to promote his addition of the filioque by combining normative tradition and consensual adaptation, and he wisely did not try to impose this on a wider Christianity.

In his final chapter, Drews reflects upon the cultural and religious parameters that underlay the strategies of legitimization in the two cases. This is rather risky terrain. Many authors have conducted similar discussions, with the assumption of quasi-genetic differences that articulated themselves inevitably in different practices and approaches, and the conclusions of many of these discussions were as predictable as they were useless. The present author, in contrast, conducts his discussion expertly. He strikes a convincing balance between broad lines of development (such as, for instance, the different understandings of traditions from Antiquity) and concrete historical processes.

At some points, it is clear that Drews’ main background is not in Middle Eastern history. However, a certain imbalance is inevitable in such a broad project and the isolated inaccuracies do not undermine the main argument. For most of the book, he convincingly integrates the existing scholarship into his argument. In addition, he refers to a wide range of primary sources that go beyond the usual narrative texts, including numismatic evidence. A minor quibble is that the strong reliance on the works of Thomas Nagel and their underlying assumptions of inherent ‘otherness’ is somewhat discomfiting, and may have encouraged rather debatable comments on modern Islamic societies in the final part of the book.

In sum, Drews’ aim is ambitious, but he is ultimately successful and he is to be congratulated for having written the standard work on this topic. The comparison provides unique insights and is fascinating for anyone working with comparative approaches, but even scholars who focus on either of the two spheres will profit from the discussion. Most importantly, this is a splendid example of cross-cultural comparison that is of relevance for similar projects, irrespective of the concrete contexts.