How to Plan a Crusade: Reason and Religious War in the High Middle Ages by Christopher Tyerman (review)

As its title explains, this book is not about the (Jerusalem) crusades themselves (how they unfolded once they were unleashed) but rather about the thought and preparations that went into making them happen. The emphasis here is on the importance of distinguishing between a vision—however unrealistic—and the pragmatic groundwork and reasoned strategizing that had to be engaged in to translate that vision into reality. By explaining in great detail the effort put into the logistics involved (mobilizing, recruiting, coordinating, transporting, budgeting, and so forth), the writer dispels the notion that, in this case, irrational human passions determined behavior. Instead, the pre-Enlightenment High Middle Ages are shown to have been an era of rationalism, as long as we measure rationality not by the ends defined but by the calculative methodology employed to achieve them. The reader may well have ringing in her ears Polonius’s aside in Hamlet about method and madness, but the author’s point is well taken, and one is reminded—as the writer encourages one to be—of the madness of many state-of-the-art wars being carried out today. This is an advanced reader’s scholarly work, presuming general knowledge of the subject and marshaling the minutest of relevant data, excavated from numerous archives and other sources, in order to draw a very real picture of the plans and ambitions—ecclesiastical and mundane—of popes and paupers, lords and knights, and kings and their subjects. The frenzy that spread across Europe in pursuit of the earthly kingdom of God is well shown by the writer to have been made possible only by means of the most calculating of measures.