Die Walküre
The other Valkyries are wondering where Brünnhilde is.  They see her coming on her horse, but instead of a hero she is carrying a woman (it is Sieglinde).  The Valkyries are angry with Brünnhilde because she disobeyed Wotan.  Sieglinde wants to die, but when she is told that she has a baby in her womb she asks Brünnhilde to save her.  She escapes into the forest with bits of Siegmund’s sword.  One day the baby she is now bearing will grow up, become a hero, and use the bits to make another sword.