In his Habilitationsschrift Johannes Hahn asks to what extent the Christianisation of the late Roman empire was accompanied by religious violence. He thinks that violent incidents in which, in the wake of the Constantinian revolution, Christians and pagans or Christians and Jews were involved were not simply rooted in religious conflict but point to deep-seated social, economic, ethnic and other motivations which in each case need careful analysis. Hahn demonstrates the complexity of the problem by choosing four examples (Alexandria, Antioch, Gaza and Panopolis in Upper Egypt) for which the evidence is particularly rich and where religious violence is obvious. He studies the social institutions and asks for the structural and social consequences of each individual controversy. Incidents include the ups and downs of the episcopate of Athanasius and the destruction of pagan temples such as the Serapeion in Alexandria, the pagan restoration in Antioch under the emperor Julian, the events at Gaza under Bishop Porphyry (sedit 395–420) and the destruction of paganism instigated by Shenouda the Archimandrite (sedit c. 385–c. 466). Hahn uncovers many sources that are little known even among patristic scholars and evokes a vivid picture of the complex religious situation which varies from region to region. He finds that in late antiquity religious conflict was less common than is generally thought. Often the local bishop who had risen to the top of the local social pyramid played a key role in this respect. Frequently, violent riots broke out over episcopal appointments. In addition, bishops played a vital part in quarrels with competing religious groups. In order to enforce their interests the bishops often called upon the power of the state. The political administration tended to help the bishops, but was otherwise rather passive. Church members were another group upon which bishops could rely to further their cause, yet, again, the simple believers tended not to become active on their own initiative. Hahn's book contains numerous important observations and his treatment of the examples chosen is, on the whole, impeccable. Yet he tends to overstate his case, as far as the late Roman empire as a whole is concerned. Rather, his examples demonstrate the diversity of religious violence in that period.