Clancy dates King Arthur's birth at about A.D. 460 and his death at about 520. These were unsettled times; the Roman power that had occupied, controlled, and protected Britain from invasion for more than three hundred years had withdrawn from the island in the face of barbarian threats and political instability at home. Several Germanic tribes, especially the Saxons, began to take possession of eastern Britain. Clancy believes that a man named Arthur commanded a company of assault troops who effectively repulsed the invaders and ushered in a peaceful, albeit brief, era for the Celtic peoples of Britain. Although Clancy grounds his book in the events of King Arthur's time, he discusses literature dated from the sixth century up through the present and, in discussing how the Arthurian legend has grown over the years, offers a glimpse of some 1500 years of history.