This article offers a detailed examination of the military retinues of the earls during Edward I's wars in the twelve-nineties and early thirteen-hundreds. While work has been done on the English armies in the Hundred Years' War, military retinues in Edward I's reign, the first for which voluminous records survive, have been largely neglected.The article discusses the sources available, analyses the various ways in which the earls created their military followings and argues that continuity of service was much greater than has previously been imagined. Such findings have important implications both for studies of the nobility in the late thirteenth century and for work on military retinues in the Hundred Years' War.From the outbreak of war with France in 1294 until Edward I's death in July 1307, the English fought thirteen campaigns in Wales, Scotland, Gascony and Flanders. 1 This contrasted with the first twenty-two years of the reign when just three campaigns took place, and meant that, to an unprecedented extent, a significant proportion of the most influential men in England were involved in regular military activity. 2 Continual service in the king's wars forced the magnates to recruit large numbers of men to serve with them more frequently than ever before. A bureaucratic change among the chancery clerks means that, for the first time, we are able to identify the names of many of those recruited by the magnates, and it provides us with the opportunity of forming a partial, if frustratingly incomplete, picture of how these military retinues were created. 3 In his early work, K. B. McFarlane had regarded the wars of Edward I as the key catalyst in the development of the indentured retainer, a view that he and others subsequently revised, coming instead to see retaining as something driven by lords'