This project examines how and why concepts of atrocity came to be an important part of delineating the limits of war. A cross-cultural study of a pivotal time in the development of the conduct and perceived limits of war, the project investigates the crusades to the Holy Land from 1095-c.1300 as well as crusades conducted against other perceived enemies such as heretics, pagans and political enemies in Europe, the Baltic, the Greek East and around the Mediterranean. The project thus considers understandings of atrocity in a range of cultural, social and religious contexts and encounters in order to investigate how atrocity was understood, represented and used across time and place. It considers atrocity from the perspective of perpetrators, victims and bystanders. By undertaking a sustained social and cultural analysis of the ways in which atrocity was understood in a range of environments across time, this project will show how atrocity in war becomes part of justification, regulation of conduct, and cultural thinking in regard to war. Given modern global attention to identifying and prosecuting atrocities in war, it is surprising that there has been no social and cultural study of atrocity in a long historical perspective. This project will provide the first such history. The time of the crusades was a critical historical moment when concepts of atrocity were increasingly used to describe, legitimise and critique the practice and nature of war. This is because the crusades, which were conducted in many theatres of war across Europe, the Middle East and the Mediterranean from 1095, brought together a multitude of people of different religions, ethnicity, status and culture. These encounters were, initially at least, rooted in the military hostility of holy war and the sources that describe these varied conflicts are rich sources for a cultural history of medieval war. At the same time, from the late eleventh century, there was both a revival of Augustinian just war theory in the west and a revival of the notion of jihad in the Islamic world. These developments were also due to the formulation of the crusade as a new instrument of holy war and the increased preaching of jihad as an effective response to the crusade, especially from the twelfth century. The crusading period was thus a turning point for the conceptualisation of the nature and conduct of war in general in both Islamic and Christian cultures.