He was appointed minister to France in 1796 and a year later participated in the unsuccessful diplomatic peace mission to avert a naval war with France, known as the XYZ Affair. Pinckney ran with John Adams for the Federalist Party and was the unsuccessful Federalist candidate for President in 1804 and 1808. His brother Thomas (1750–1828) was also a diplomat and was responsible for negotiating the Treaty of San Lorenzo (popularly known as Pinckney’s Treaty) with Spain in 1795, winning US trading rights at New Orleans, free navigation of the Mississippi River, and an agreed southern boundary between the USA and Florida.