While the image of the Vikings has been rehabilitated in the past few years, showing them as peaceful farmers and artisans, some evidence of cruel and bloodthirsty behavior does exist. In Smithsonian's blog Past Imperfect, Mike Dash looks at the more brutal side of the Norsemen, and the fact of torture such as the "blood eagle."
From the blog:
There have always been problems, in short, for historians who want to suggest that the Vikings were peace-loving and misunderstood, and of these the most intractable is their penchant—at least as portrayed in chronicles and sagas—for gory ritual killings. Among several eminent victims of this practice, we might number the Saxon king Edmund the Martyr—who died in 869, tied to a tree (says the 10th-century Passio Sancti Eadmundi), thoroughly scourged and then used for target practice by Danish archers “until he was all covered with their missiles as with bristles of a hedgehog”—and Ælla, king of Northumbria, who in 867 is said to have met an even more unpleasant fate at Viking hands in a rite known as the “blood eagle."