On 15 August 1782 he was sent by the States-General to the peace negotiations between the participants in the American Revolutionary War in Fontainebleau as an Envoy Extraordinary and Minister Plenipotentiary (together with ambassador Mattheus Lestevenon) for the Republic to negotiate the 1784 treaty that ended the Fourth Anglo-Dutch War (to which he was a signatory). While in France they negotiated the Treaty of Fontainebleau (1785) with Holy Roman Emperor Joseph II which maintained the continued closure of the Scheldt, in exchange for certain concessions from the Republic. In 1787 he was recalled, but remained as a private citizen in France until 1792 ("Rue Neuve des Mathurins"). In 1794 he acted ( together with Ocker Repelaer van Driel) as envoy to the French Republic to attempt to conclude a separate peace in the War of the First Coalition between the Dutch and French Republics, but the collapse of the Dutch defense prevented this from coming to fruition.