The mounted, armoured knight is one of the most potent symbols of medieval civilisation, a persistent image leaping out from the folios of illuminated manuscripts and the texts of the chroniclers of chivalry. For much of the middle ages the armoured warhorse was what defined a man-at-arms at muster, and what set him apart as a member of the military class. However, despite the status of the knightly warrior in medieval society, the military service of the later medieval English aristocracy remains an unaccountably neglected subject, while the warhorse itself has never attracted a major study based upon archival sources. This book seeks to open up what are, then, effectively new fields of research.