81. In a memorable duel at Aix-la-Chapelle (A.D. 820),
before the emperor Lewis the Pious, his biographer observes,
secundum legem propriam, utpote quia uterque Gothus erat,
equestri pugna [proelio] congressus est (Vit. Lud. Pii. c.
33, in tom. vi. p. 103). Ermoldus Nigellus (l. iii. 543-628,
in tom. vi. p. 48-50), who describes the duel admires the
'ars nova' of fighting on horseback, which was unknown to
the Franks.