The reign of Æthelred 'the Unready' (978–1016) is known to us mainly from a series of annals in the Anglo-Saxon Chrolicle, written at or after its close and accordingly conveying an impression of gathering doom as Viking armies ravaged the country and eventually, under the leadership of Swein Forkbeard and Cnut, brought about its conquest. Dr Keynes is here concerned to establish what light the royal diplomas issued in King Æthelred's name throw on this unhappy and notorious period. He first considers the general issues that bear directly on the value of royal diplomas as historical evidence for all periods of Anglo-Saxon history, discussing the circumstances under which these documents have been preserved, the techniques available for their criticism, and the arrangements that existed for their production. He then demonstrates how a detailed analysis of Æthelred's diplomas can transform our understanding of this troubled reign. On a practical level they provide invaluable evidence on the operation of royal government, and on a personal level they afford a remarkable insight into the relations between the king and his councillors, suggesting a picture of political manoeuvring and court intrigue which compensates for the chronicler's emphasis on the struggle against the marauding Vikings. By placing the familiar account of incessant warfare in the context of these domestic affairs it becomes possible for the first time to see the reign in its true perspective.