The age of the crusades is one of the most important epochs in the history of humanity. And yet, so far we do not have a full and complete answer to the question of what exactly the crusades were. How did the idea of the crusade come about? Who were the crusaders? How many crusades were there in total? How did they impact on the medieval civilization? What caused the crusades to end? The author of this comprehensive study ponders over these and many other issues by placing the events in their social, political and intellectual context and by focusing on how crusading evolved in theory and practice. This book suggests a new and stimulating view of the popular topic.