The blood eagle is a ritualized method of execution, detailed in late skaldic poetry. According to the two instances mentioned in the Sagas, the victim (always a member of a royal family) was placed prone, the ribs severed from the vertebral column with a sharp implement and the lungs pulled through the opening to create a pair of “wings”. There is a continuing debate about whether the ritual was a literary invention, a mistranslation of the original texts or an actual historical practice.
There are only two incidents and one oblique reference in Norse literature which mention the ritual. The primary versions both have some commonalities: the victims are both noblemen (Halfdan Haaleg or "Long-leg" was a prince; Ælla of Northumbria a king) and both of the executions were in retaliation for the murder of a father.
In the Orkneyinga saga, the blood eagle is described as a sacrifice to Odin. Torf-Einarr has Harald Fairhair's son Halfdan Long-Leg ritually executed:
Einarr made them carve an eagle on his back with a sword, and cut the ribs all from the backbone, and draw the lungs there out, and gave him to Odin for the victory he had won.
Snorri Sturluson's Heimskringla contains an account of the same event described in Orkneyinga saga, with Einarr actually performing the deed himself:
Afterwards, Earl Einarr went up to Halfdan and cut the "blood eagle" on his back, in this fashion that he thrust his sword into his chest by the backbone and severed all the ribs down to the loins, and then pulled out the lungs; and that was Halfdan's death.
In Þáttr af Ragnars sonum, the "Tale of Ragnar's sons", Ivar the Boneless has captured king Ælla of Northumbria, who had killed Ivar's father Ragnar Loðbrók. The killing of Ælla, after a battle for control of York, is described thus: