The god has just vanished amid the mutterings of thunder, expressive of his wrath if any one dare to disobey his behests, when Siegmund and Sieglinde suddenly appear upon the mountain side.  They are fleeing from Hunding, and Sieglinde, who has discovered when too late that Siegmund is her brother, is so torn by remorse, love, and fear that she soon sinks fainting to the ground.  Siegmund, alarmed, bends over her, but, having ascertained that she has only fainted, makes no effort to revive her, deeming it better that she should remain unconscious during the encounter which must soon take place, for the horn of the pursuing Hunding is already heard in the distance.

Siegmund has just pressed a tender kiss upon Sieglinde’s fair forehead, when Brunhilde, the Walkyrie, suddenly appears before him, and solemnly warns him of his coming defeat and death.  He proudly tells her of his matchless sword, but she informs him that his reliance upon it is quite misplaced, for it will be wrenched from his grasp when his need is greatest.  Then she tries to comfort him by describing the glory which awaits him in Walhalla, whither she will convey him after death.

Siegmund eagerly questions her, but, learning that Sieglinde can never be admitted within its shining portals, passionately declares he cannot leave her.  He next proposes to kill her and himself, so that they may be together in Hela’s dark abode, for he will accept no joys which she cannot share:—­

   ’Then greet for me Valhall,
    Greet for me Wotan;
    Hail unto Waelse,
    And all the heroes! 
    Greet, too, the graceful
    Warlike mist-maidens: 
    For now I follow thee not.’

Brunhilde’s heart is so touched by his love for and utter devotion to Sieglinde, and she is so anxious at the same time to fulfil Wotan’s real wish, in defiance of his orders, that she finally allows compassion to get the better of her reason, and impulsively promises Siegmund that she will protect him in the coming fray.  At the same moment Hunding’s horn is heard, and Brunhilde disappears, while the scene darkens with the rapid approach of a thunderstorm.  Such is the darkness that Siegmund, who has sprung down the path in his eagerness to meet his foe, misses his way, while Sieglinde slowly rouses from her swoon, muttering of the days of her happy childhood when she dwelt with her family in the great wood.  Suddenly, the lightning flashes, and Hunding and Siegmund, meeting upon a ridge, begin fighting, in spite of Sieglinde’s frantic cries.

As the struggle begins, Brunhilde, true to her promise, hovers over the combatants, holding her shield over Siegmund and warding off every dangerous blow, while Sieglinde gazes in speechless terror upon the combatants.

But in the very midst of the fray, when Siegmund is about to pierce Hunding’s heart with his glittering sword, Wotan suddenly appears, and, extending his sacred spear to parry the blow, he shivers the sword Nothung to pieces.  Hunding basely takes advantage of this accident to slay his defenceless foe, while Brunhilde, fearing Wotan’s wrath and Hunding’s cruelty, catches up the fainting Sieglinde and bears her rapidly away upon her fleet-footed steed.