The fourteenth-century Icelandic Edwardsaga chronicles the life of Edward the Confessor, the last Anglo-Saxon king of England (reigned 1042–1066). It also describes how, in the years after the Norman Conquest in 1066 -- when William the Conqueror invaded England and was crowned king -- 350 ships carrying English warriors set out for Constantinople. There, the Byzantine emperor employed the Anglo-Saxons as members of the Varangian Guard, an elite unit of foreign soldiers that served as his personal army. Such was their loyalty, says the Edwardsaga, that the emperor deeded them land six days' sailing north of Constantinople. There, presumably on...