This is a study of the warfare waged between 1066 and 1135 by the Anglo-Norman kings of England - William the Conqueror, William Rufus and Henry I.

Bringing together the two major trends in recent medieval military history, the study of military organisations and the study of campaigns, Stephen Morillo illuminates the interrelationship of military organisation and social and political structures. The familia regis, the king's military household, emerges in a central role: its influence extended from castle garrisons, engineering and supply to the organisation of armies; its permanence and professionalism dictated tactical practices in battle.

By contrast, the military importance of the feudal system is considerably reduced.

Stephen Morillo's examination of the roles of armies and castles and the normal activities of warfare shows why ravaging and plundering the land and besieging castles were far more common than pitched battles. He analyses siege and battle tactics in the context of social and political influences, administrative structures and campaign patterns, and he proposes a connection in most pre-modern warfare between government strength and infantry quality.