Jonathan Riley-Smith was Emeritus Dixie Professor of Ecclesiastical History at the University of Cambridge, UK. His many publications on the Crusades include What Were the Crusades? (2009), The Crusades, Christianity and Islam (2008) and The First Crusade and the Idea of Crusading (1986).Susanna A. Throop was Professor and Department Chair of History at Ursinus College, USA. She is the author of The Crusades: An Epitome (2018) and Crusading as an Act of Vengeance, 1095-1216 (2011). She is also the co-editor of The Crusades and Visual Culture (2015) and Vengeance in the Middle Ages (2010).