Quick summary of Joan of Arc?

Why do we say "Joan of Arc". She was called Jeanne d'Arc, in French. But d'Arc was her family name.

• She wasn't from a town called "Arc" Shouldn't we say Joan d'Arc? The French couldn't say Mary of Connor, talking about Mary O'Connor. Joan of Arc was from Domrémy,in Loraine, and her father's name was Jaques d'Arc, Her father, however, was from Arc-en-Barrois, in Champagne.

• Answer:

  "Joan of Arc did not come from a place called Arc, but was born and raised in the village of Domrémy in what was then the northeastern frontier of France. In the English language her first name has been repeated as Joan since the fifteenth century because that was the only English equivalent for the feminine form of John during her lifetime. Her surviving signatures are all spelled Jehanne without surname. The surname of Arc is a translation of d'Arc, which itself is a nineteenth-century French approximation of her father's name. Apostrophes were never used in fifteenth-century French surnames, which sometimes leads to confusion between place names and other names that begin with the letter D. Based on Latin records, which do reflect a difference, her father's name was more likely Darc. Spelling was also phonetic and original records produce his surname in at least nine different forms, such as Dars, Day, Darx, Dare, Tarc, Tart or Dart." Source and further information: http://en.wikipedia.org/wiki/Name_of_Joan_of_Arc