There may indeed have been a ship named La Belle Paule, but every reference I've seen to the frigate that brought home Napoleon's remains has spelled it Belle Poule (or Belle-Poule).
To modern English speakers (especially American ones), the idea of naming a ship "the beautiful chicken" may seem a little bizarre. But different cultures - and different generations - seem to create different associations with birds and animals. When I was in college, one of the nastiest ways to insult somebody was to call him a turkey. (Come to think of it, I wouldn't take the term as a compliment now.) But Benjamin Franklin saw nothing inappropriate about recommending that the wild turkey be named the national bird of the United States.
I can only conclude that "beautiful chicken" (or perhaps "beautiful hen") was a term of endearment in eighteenth- and nineteenth-century France. It probably is no coincidence that Franz Josef Haydn's Symphony #83, which he wrote for a Parisian orchestra in 1787, has the title "La Poule."
Youth, talent, hard work, and enthusiasm are no match for old age and treachery.