THE thirteenth century was an era of growing population, extensive land clearance, expanding towns and rapid social mobility. Governments grew more powerful and legal systems more complex. Distinctions of legal and social rank also became more elaborate. All these developments affected the aristocracy of thirteenth-century Europe, but none will serve to define the aristocracy itself as a group within society. Rather, the aristocracy of thirteenth-century Europe defined itself by its self-conscious adherence to a European-wide set of common cultural values and assumptions embodied in the cult of chivalric knighthood. Before we discuss how the aristocracy changed, we must first know who they were. It is with chivalry, therefore, that we must begin.

By the end of the twelfth century, the ideology of chevalerie had gained wide-spread acceptance among the mounted, heavily armoured warriors of western Europe. Contemporaries were increasingly aware that together these chevaliers could be conceived of as constituting a distinctive order within society. Like the other orders of late twelfth-century society, this ordo militaris comprised a very wide range of social ranks, from kings and emperors at the top, down to the landless warriors who in turn shaded off into the ranks of the wealthier peasantry. Chivalric ideology did not originate with the great lords, and in the empire particularly they were latecomers to it. But by the last decades of the twelfth century it was these great lords who, through their patronage of tournaments, heraldry and literature, fostered a notion of chevalerie as a social order which bound together men of such otherwise disparate status in life, and who, by identifying themselves with it, identified chevalerie with true noblesse. Not all the men called milites in Latin sources were noble in the year 1200, and not all nobles would have been flattered to be called milites or even chevaliers.