AS WITH EVERY BOOK, this one too has its story. The idea for the volume originated in conversations in 2016–2017 between Radosław Kotecki and Carsten Selch Jensen during a joint project devoted to the role of the medieval clergy in warfare. These discussions, soon joined by Stephen Bennett and some other contributors to this volume, centred on concern for the research gap in the historiography of relationships between Christianity and war in the Middle Ages. At the time, we shared the conviction that studies on this issue predominantly focused on the West and the South of the European continent. Regions located more to the East and North, which converted to Christianity only around 1000 or even much later, were largely neglected. Being aware of both these deficiencies, and also the potential of the local sources and research circles, we decided to prepare a collection that would offer some fresh perspectives. The intention would also be to move away from perceiving these issues only through the prism of crusade ideology. The result is this volume, co-created by an international group of medievalists from Czechia, Denmark, Estonia, Finland, Hungary, Norway, Poland, and the United Kingdom. Ultimately, fifteen scholars contributed to the book. The structure of the team was, however, fluid. Several initial project members had to withdraw because of other commitments; however, their ideas also helped shape the outcome.

This volume owes a lot to several people, and the editors wish to thank everyone who has been involved in bringing it to fruition. Particular thanks go to the authors for timely submission of their chapters, and for their patience during the editing and production process. In particular, we wish to thank Jacek Maciejewski, whose counsel and help have proved invaluable throughout all stages of this project. Special thanks go to the anonymous peer reviewer, who approved the book's publication with Arc Humani-ties Press and Amsterdam University Press, and suggested valuable improvements. We would also like to thank Christian Raffensperger for his careful reading of the manuscript, and valuable comments, as well as for his acceptance of the book into the Beyond Medieval Europe series. Anna Henderson from Arc Humanities Press proved to be very helpful and supportive at every stage of its production and deserves fulsome praise.