On July 7, 1798, the United States Congress annulled the Treaty of Alliance we had signed with France during the American Revolution, leading to the undeclared “Quasi-War” with France.
This came as a result of the XYZ affair. In July 1797, three Diplomats from the US: Charles Cotesworth Pinckney, John Marshall (who would later become the fourth Chief Justice of the United States Supreme Court), and Elbridge Gerry traveled to France to negotiate problems that threatened to lead to war between the US and France. Among these problems were the French seizure of neutral vessels that traded with Great Britain, with whom they were then at war. Great Britain had likewise been neutral ships trading with France but the US had worked out an accommodation with Great Britain via the Jay Treaty.
When they attempted to seek these negotiations the French Foreign Minister Talleyrand demanded bribes and a loan before formal negotiations could begin. While this was common practice in Continental European diplomacy to the Americans it was highly offensive. Despite nearly a year of attempts to meet for official negotiations Pinckney and Marshall left France in the Spring of 1798 without ever engaging in any formal negotiations. Gerry, hoping to avoid all-out war as Talleyrand had threatened to declare war if he left, remained until someone with more authority could replace him. It was not until later in 1798 that Talleyrand sent representatives to the Hague to open negotiations with Williams Van Murray, allowing Gerry to return home in October of 1798
Documents released by the Adams administration, in which the names of French Diplomats Hottinguer, Bellamy, and Hauteval were replaced by the letters “X”, “Y”, and “Z” respectively, leading to the name “The XYZ affair” being attached to the incident caused outrage in the US. Federalists used the incident as an excuse to build up the US’s military. (Never let a good crisis go to waste.) Considerable anger was directed at Jeffersonian Democratic Republicans for their pro-French stance and Gerry (still at that time in France) although himself non-partisan, was attacked as having significant responsibility for the commission’s failure.
The upshot of this outrage was that Congress annulled our Treaty of Alliance with France on June 7, 1798. This began the “Quasi-war”. Neither the United States nor France declared war on each other but for a period of two years they fought naval engagements attacking each others shipping in the West Indies. The nascent US Navy along with 365 privateers (privately owned vessels armed and authorized via “Letters of Marque and Reprisal” to fight our nation’s enemies) fared surprisingly well against the French.
The success of the US and Royal Navies (the Royal Navy was also operating against the French in that area although not in any joint capacity with the United States), along with the more conciliatory position of First Consul Napoleon Bonaparte, severely reduced the activity of the French forces in the West Indies. The Convention of 1800, on September 30 of that year, ended the Quasi-war.