Battle ready

For most of history, religion and war have been the most powerful social instincts of mankind and its chief collective activities. In the crusades, they combined to create a movement of great emotional power, which convulsed Europe in the 12th century and retained its appeal to the military classes until the end of the Middle Ages. One might expect people who embarked on a great war with such intense spiritual exultation to be unconcerned with practical planning. And there were some who believed that these mundane matters should be left to the Holy Spirit to sort out. But they tended to come to a sticky end. For most crusaders, holy war was a serious business, calling for professional organisation, ample finance and meticulous logistical preparation.

Christopher Tyerman is the author of outstanding books on the crusades, notably God’s War (2006), which remains the best modern account of the whole subject. In How to Plan a Crusade, he tackles the whole question of crusade preparation.