Although he was not an heir to the French throne, general Claude François de Malet attempted a coup in France, in 1812.
After escaping from captivity, he informed the National Guard that Napoleon had died in Russia.
He succedeed to release two generals, arrested a few others and tried to seize the power in Paris.
The same day, he presented letters to Colonel Pierre Doucet that stated Napoleon had died on 7 October. However Doucet had knowledge of letters written by Napoleon after that date and went suspicious.

Shortly after, Malet was arrested and then executed.

Article from wikipedia : [Malet coup of 1812][1]


  [1]: https://en.wikipedia.org/wiki/Malet_coup_of_1812