These studies span the period from the origins of the crusading movement in the 11th century until its final active phase during the Renaissance. Some of the articles spring from Norman Housley's work on crusading against Christian heretics, mercenary companies and lay powers which were involved in conflict with the Church. Others reflect his interest in the way crusading developed after the fall of the Holy Land to the Muslims in 1291. A third group looks at other forms taken by religious warfare in Europe during the late Middle Ages and Renaissance. Certain themes recur throughout. One is the variety of ways in which war in God's name was portrayed and justified. Another is the conflict of interest brought about by the diversity of crusading in the period from c.1200 onwards. Above all, the author shows the complexity, longevity and significance of a movement whose impact on medieval society was massive and whose repercussions were profound.