What was unusual about the 19-year-long relationship between Francois Fournier-Sarloveze and Pierre Dupont de l'Etang?

As a young officer in Napoleon's Army, Dupont was ordered to deliver a disagreeable message to a fellow officer, Fournier, a rabid duellist. Fournier, taking out his subsequent rage on the messenger, challenged Dupont to a duel. This sparked a succession of encounters, waged with sword and pistol, that spanned decades. The contest was eventually resolved when Dupont was able to overcome Fournier in a pistol duel, forcing him to promise never to bother him again.