On 14 September 1794, at the village of Doel, on returning from one of many missions to deliver secret instructions to forts in the Dutch Republic, he became trapped behind enemy lines and received such serious bayonet wounds that he was left for dead; he lost his right eye in this skirmish.[citation needed] In 1814, Klemens von Metternich sent him to negotiate with the King of Naples, Joachim Murat, who signed a secret peace treaty with Austria in order to keep his throne.Metternich's other intrigue was to try to distance Prince Eugene (stepson of Napoleon and son-in-law of King Maximilian I Joseph of Bavaria) from the French.Murat dispatched General Carrascosa with a division of Neapolitan troops to prevent Neipperg's corps linking up with Bianchi and the Austrian main body.With the threat of Neipperg's large force approaching his flank, Murat had to order the Neapolitan army to withdraw, turning Tolentino from a potential Napoleonic victory into a defeat.From this union, four children were born, the first two before the marriage, whilst Marie-Louise was still legally married to Napoleon: Neipperg died in Parma on 22 February 1829 of a heart condition.His descendants with the Duchess Maria-Luigia, the Princes von Montenuovo, intermarried with the Austro-Hungarian nobility and served as courtiers and diplomats at the Imperial Hofburg in Vienna, dying out in the male line in 1951.