In its most basic terms, war depends upon getting men to risk their bodies, to override the instinct to flee danger so as to preserve life, and instead to stand and fight, and if necessary, to fight to the death. The means by which this is achieved can be understood variously as the effects of the noble virtue of courage at one end of the spectrum, and the despicable hardening of men into beasts at the other. The Middle Ages has not shaken off its reputation as a violent, conflict-ridden age (a view not without some justification), nor has it put to rest the charge that its codes of chivalry existed to keep violent men in check. Yet learned, Latinate treatises in this period (on natural philosophy, and on governance, among other subjects) confront the difficult ethics of war, and how it is men are brought to engage in battle and sacrifice their lives in its cause. The answers these treatises offer draw on complex understandings of human physiology and psychology. Towards the end of the fourteenth century and into the fifteenth, some such treatises, like Giles of Rome's widely influential De regimine principum, are translated into vernacular languages or are drawn on by vernacular authors writing on war and chivalry. This essay focuses on these learned ideas about physiology and psychology as they appear in a set of late medieval English writings on war, principally those translating or reworking (in whole or in part) Giles's De regimine principum and Vegetius’ De re militari.

Inquisitio, a process first codified in the canons of the Fourth Lateran Council of 1215, was an important means of investigating crime in general and heresy in particular in the later medieval period. For the most part, it has been the subject of historical rather than cultural investigation: scholars have focused on its role in the development of the medieval church and its laws, and on the dynamics of heresy inquisition in medieval Europe and, more recently, England. To view it only as a tool in the fight against heresy, however, is to overlook both its broader significance and its imbrication with other mechanisms of medieval canon law. Even in the English ecclesiastical courts, inquisitio had other uses: it was, for example, most commonly used to regulate sexual relations (fornication, adultery, bigamy, etc.); it was bound up with sanctions like excommunication and public penance, as well as confession, sacramental or otherwise; and, perhaps most significantly, since the law stipulated that inquisitio could only be initiated when someone was widely held to be guilty of a specific crime, it was intimately associated with questions of reputation and social standing. It is hardly surprising then that in the centuries following Lateran IV, the applications of inquisition moved beyond the boundaries of the ecclesiastical courts into the fields of exemplarity, rhetoric and poetry.