Viking is such a vivid word, steeped in imagery and blood. The Viking Age began and ended in England. Its first act in AD 789 was a murder on a beach in Dorset; its last, some two and a half centuries later, was the crowning of a Dane in London as king of a united England. In between, the Vikings waged war on four continents, they besieged London, Paris and Constantinople, founded Russia and the Duchy of Normandy and very nearly snuffed out Anglo-Saxon England. Yet these days they are seen more as traders and explorers than as warriors. This new history returns the Vikings to their former...