The kings of Castile maintained a personal cavalry guard through much of the fifteenth century, consisting of practicing Muslims and converts to Christianity. This privileged Muslim elite provides an interesting case-study to propose new theories about voluntary conversion from Christianity to Islam in the Iberian Peninsula, as well as the ways of assimilation of such a group into the local and courtly environments where they lived thereafter. Other subjects involved are the transformation of royal armies from feudal companies to regimented, professional forces including a well-trained...