Introduction
Sigmund was a son of Volsung and twin brother of Signy. At Signy's wedding feast to King Siggeir, a one-eyed stranger (Odin in disguise) thrust a sword into a great tree and declared it for whoever could draw it out; only Sigmund succeeded.
Family
Vengeance and a Final Battle
Siggeir's envy over the sword led him to betray and kill Volsung and Sigmund's brothers; Sigmund alone escaped, aided by his sister Signy, and the two eventually engineered a terrible revenge on Siggeir together, including Signy conceiving a son by Sigmund in disguise (Sinfjotli) specifically to ensure a sufficiently pure-blooded avenger. Sigmund later married twice — first Signy's line notwithstanding, then formally to Hjordis — and fathered Sigurd in his old age. He died in his final battle when his own sword, the one drawn from the tree, shattered against the spear of a disguised Odin, who had decided Sigmund's part in the story was complete; the shards were kept by Hjordis and later reforged by Regin into Sigurd's sword, Gram.
The Volsunga Saga and the Poetic Edda preserve the Norse-Icelandic form of this legend; the German Nibelungenlied recounts substantially the same events under different names (Sigurd as Siegfried, Brynhild as Brünnhilde, Atli as Etzel/Attila), reflecting a shared Germanic legendary tradition rather than a single fixed text.