The military religious orders emerged during the Crusades as Christendom's stormtroopers in the savage conflict with Islam. Some of them still exist today, devoted to charitable works. The Monks of War is the first general history of these orders to have appeared since the eighteenth century. The Templars, the Hospitallers (later Knights of Malta), the Teutonic Knights and the Knights of the Spanish and Portuguese orders were "noblemen vowed to poverty,...