Lohengrin

Members of this order are sent out in secret to provide lords to kingdoms that have lost their protectors and Loherangrin is eventually called to this duty in Brabant, where the duke has died without a male heir.

The story appears in the two versions of the tale Naissance du Chevalier au Cygne,[1] which describes the Swan Knight Elias arriving to defend the dispossessed Duchess of Bouillon.

[3] The story was picked up and expanded in the late 13th-century Lohengrin by a certain "Nouhusius" or "Nouhuwius", who changed the character's name and tied the romance's Grail and Swan Knight elements into the history of the Holy Roman Empire.

[4] The story follows Wolfram closely but adds certain details – notably, Princess Elsa's questioning of her husband occurs only after prodding by an antagonist who spreads rumors that Lohengrin is not of noble blood – that extends the material into a full romance.

[7] While King Henry the Fowler tries to assemble forces in Brabant to combat the Hungarian invasions, Lohengrin appears on the Scheldt River to defend Princess Elsa from the false accusation of killing her younger brother Gottfried (who turns out to be alive and returns at the end of the opera).