known as the blood eagle is a matter of historical contention, particularly since in Norse imagery the eagle was strongly associated with blood and death. Saxo Grammaticus in Gesta Danorum tells the following about Bjørn and Sigvard, sons of Ragnar Lodbrok and king Ælla: Other accounts Another possible oblique reference to the rite appears in Norna-Gests þáttr. There are two stanzas of verse near the end of its section 6, "Sigurd Felled the Sons of Hunding", where a character describing previous events says: {| |style="padding-right:1em;"| |style="padding-left:1em;"|Now is the bloody eagle with a broad sword carved on the back of the killer of Sigmund. Few were better kinsmen of kings, who rule land and gladden the raven. |} Authenticity There is debate about whether the blood eagle was historically practiced, or whether it was a literary device invented by the authors who transcribed the sagas. No contemporary accounts of the rite exist, and the scant references in the sagas are several hundred years after the Christianization of Scandinavia. In the 1970s Alfred Smyth supported the historicity of the rite, stating that it is clearly human sacrifice to the Norse god Odin. He characterized St. Dunstan's description of Ælla's killing as an "accurate account of a body subjected to the ritual of the blood eagle". Roberta Frank reviewed the historical evidence for the rite in her "Viking Atrocity and Skaldic Verse: The Rite of the Blood-Eagle", where she writes: "By the beginning of the nineteenth century, the various saga motifs—eagle sketch, rib division, lung surgery, and 'saline stimulant'—were combined in inventive sequences designed for maximum horror." She concludes that the authors of the sagas misunderstood alliterative kennings that alluded to leaving one's foes face down on the battlefield, their backs torn as carrion by scavenging birds. She compared the lurid details of the blood eagle to Christian martyrdom tracts, such as that relating the tortures of Saint Sebastian, shot so full of arrows that his ribs and internal organs were exposed. She suggests that these tales of martyrdom inspired further exaggeration of the misunderstood skaldic verses into a grandiose torture and death rite with no actual historic basis. David Horspool in his book King Alfred: Burnt Cakes and Other Legends, while not committing to the historical veracity of the rite, also saw parallels to martyrdom tracts. Frank's paper sparked a "lively debate". Ronald Hutton's The Pagan Religions of the Ancient British Isles: