Benwick
Benwick, Launcelot's continental realm identified with Bayonne or Beaune, besieged by Arthur, attested in 1 source.
Benwick appears in Le Morte d'Arthur as a continental realm and city associated with the family of Launcelot. In Book I, three hundred knights "of the realm of Benwick and of Gaul" join a tournament alongside King Arthur (Le Morte d'Arthur, Book I, Chapter XI). The realm thus enters the narrative as a source of military strength allied to Arthur's cause.
In the final books, Benwick becomes Launcelot's refuge after his break with Arthur. Launcelot and his company "shipped at Cardiff, and sailed unto Benwick: some men call it Bayonne, and some men call it Beaune, where the wine of Beaune is" (Le Morte d'Arthur, Book XX, Chapter XVIII). The text's casual geographical gloss -- equating Benwick with either Bayonne or Beaune -- reflects the Arthurian tradition's characteristic looseness with continental geography.
Arthur subsequently lays siege to the city: "upon the morn early, in the dawning of the day, as knights looked out, they saw the city of Benwick besieged round about; and fast they began to set up ladders" (Le Morte d'Arthur, Book XX, Chapter XX). The defenders beat the attackers from the walls, marking Benwick as the site of the final military confrontation between Arthur and Launcelot.
All three citations come from Le Morte d'Arthur. Benwick shifts function across the text: from a distant source of allied knights in Book I to the specific stage of the work's penultimate conflict in Book XX. The identification with real places -- Bayonne or Beaune -- is offered without resolution, a detail that anchors the romance geography in a vaguely recognisable France without committing to a single location.