The Lords of Battle examines the image of the comitatus, or warband, as it is portrayed in literary and historical sources from Britain's early medieval period; in so doing, it attempts to determine the extent to which this image reflects an historical reality. Through an extensive use of a variety of source material, literary, historical, and archaeological, the book investigates both the structure of the warband, and the practices and institutions which supported it.

After a review of the historical background of Dark Age Britain, Stephen Evans explores the practical characteristics of the comitatus, such as its military organisation; its internal social structure and its place within society as a whole; and the lord-retainer relationship, its duties and obligations.

He also examines the cultural, social, and economic institutions which produced and supported the warband, including the role of the court poets; the importance of the hall; hostage-taking and fosterage; and food-renders, tribute, and booty. Overall, the study provides a number of insights into the ideals and practices of Britain's Celtic and Anglo-Saxon warrior-elites during a turbulent period.