Charles XIV John of Sweden

Charles XIV & III John, also Carl John, (26 January 1763 – 8 March 1844) was King of Sweden (as Charles XIV John) and King of Norway (as Charles III John) from 1818 until his death. Before he became king, he was also the Sovereign Prince of Pontecorvo, in Southern Italy, between 1806 and 1810.
He was appointed as a Marshal of France by Napoleon I, though the two had a turbulent relationship. His service to France ended in 1810, when he was elected the heir-presumptive to the Swedish throne because the Swedish royal family was dying out with King Charles XIII.