It's amazing how much of the Arthurian mythologies have been derived from varius vague allusions in this book. Probably lots of people know about the theory of Ambrosius Aurelianus as a possible candidate for historical King Arthur because of his role in the battle at Mount Badon, but what's even more interesting is that in the book Gildas refers to a leader only by their sobriquet of "the bear", which was rendered as ursus in Latin, but in Brythonic, it would've been arth.
Also another fun fact, Gildas never refers to Dumnonia by name, instead calls it "Damnonia" presumably to reflect his condemnation.