Medieval Origins. The English epic Beowulf is a tale of bravery and vengeance. The evil monster Grendel periodically kills Hrothgar's warriors until the hero Beowulf arrives. In a heated battle, Beowulf tears Grendel's arm off and forces the mortally wounded monster to flee. Peace is briefly restored, but Grendel's mother soon appears seeking blood vengeance for the death of her son. She kills Hrothgar's favorite adviser and thus the vendetta continues. Eventually, Beowulf kills Grendel's mother, and the feud ends because Grendel has no living relatives.

Transition. The unwritten code of the blood feud demanded vengeance whenever kin or a knightly retainer was killed. These contests could end when one side was eliminated or when a killer paid wergild, or the price of a man, to the family of the victim. The money served as an example that the dead...