Love the site - I've been here often but hadn't looked at the forums nor registered until today.
Jumping in on a six-month old thread to clarify a 400 year old controversy in a digression from a 14th century forum:
Henri IV's primary claim to the throne of France was not
through his mother Jeanne d'Albret, Queen of Navarre and leader of the Huguenot party in the Wars of Religion (although she was of royal blood and would have had a strong claim of her own had the Salic Law not been in use).
Henri's father, Antoine de Bourbon, Duc de Vendome (and Duc de Bourbon-Comte de Montpensier) was the senior surviving male heir of the next-eldest male line of the Capetians to the Valois, the House of Bourbon, descended from Robert de Clermont, younger brother of Philippe III and son of Louis IX. Antoine had been favored by some as Regent when Charles IX succeeded in 1560, since he was the senior adult Prince of the Blood, but he cut a deal with Catherine de Medici and stepped aside in her favor. He died in 1562.
According to the Salic Law, Henri de Navarre was clearly the blood heir to the throne when Henri III became King and his brother Francois Duc d'Anjou died in 1584, but his claim was much more distant than earlier shifts within the Valois line (from Charles VIII to Louis XII and later to Francois I). He was only 12th cousin to the King (!), but his closest relative in the male line.
His status was also highly controversial because he was a Protestant; the Catholic League preferred his aged uncle Charles, Cardinal de Bourbon as heir. When Henri IV succeeded in 1589 and the Cardinal died soon afterwards, desperate Catholics sought a legal argument against him, going so far as to advance the claims of the Guise family as descendants of Charlemagne and therefore preferable to the Capets who, after all, had only been elected in 987 (illegally, in this argument). Henri ended the resistance and firmly established the Bourbon dynasty by adopting Catholicism in 1593 with the remark, "Paris is worth a Mass".
Sorry for the long post. I promise to stick more closely to the 14th c in future.