Movies

Or was it random whether various actors did or not?

Or did they have other Corsicans also speaking thusly, to indicate a common accent distinct from other French?

From the Early Life section of Napolean's Wikipedia page:
"Like many Corsicans, Napoleon spoke and read Corsican (as his mother tongue) and Italian (as the official language of Corsica).[33][34][35][32] He began learning French in school at the age of around 10.[36] Although he became fluent in French, he spoke with a distinctive Corsican accent and never learned to spell in French.[37] " (emphasis mine)



Anyways, whenever I am faced with dissatisfying accent work, or lack thereof, in films I think about Kevin Costner's Robin Hood film and am reminded that whatever I just watched could have been worse!