President John Adams appoints Charles Cotesworth Pinckney, John Marshall, and Elbridge Gerry as ministers plenipotentiary to France, aiming to resolve escalating Franco-American tensions over U.S. neutrality and French interference with American commerce.
In Paris, the U.S. envoys are approached by intermediaries connected to France’s foreign minister, who condition negotiations on a substantial bribe and a large U.S. loan—an episode later anonymized in U.S. documents as “X, Y, and Z.”
As coded and uncoded reports from the commissioners arrive in Philadelphia, Adams informs Congress of the mission’s failure and calls for defensive measures while initially withholding the most inflammatory details.
The diplomatic correspondence is released (with names masked as X, Y, and Z), triggering a sharp anti-French surge in U.S. public opinion and accelerating military preparedness measures.
Congress creates a separate executive Department of the Navy, moving naval administration out of the War Department as the United States prepares for maritime conflict with France.
In the climate of expected conflict with France, Congress passes the Alien and Sedition Acts (including the Alien Act, Alien Enemies Act, and Sedition Act), tightening immigration rules and restricting certain political speech—measures that become a major partisan flashpoint.
Congress votes to terminate the 1778 Treaty of Alliance and related agreements with France, marking a decisive break in the formal Revolutionary-era relationship and setting the stage for open naval hostilities.
With hostilities underway at sea, Congress passes and Adams signs legislation authorizing the use of armed force against French vessels, providing a key statutory basis for the undeclared naval war.
President Adams signs the law re-establishing the United States Marine Corps, providing shipboard and expeditionary forces that would be employed in operations connected to the Quasi-War.
State legislatures in Kentucky and Virginia adopt resolutions (authored anonymously by Jefferson and Madison) condemning the Alien and Sedition Acts as unconstitutional, signaling deepening domestic conflict during the crisis with France.
In a major early U.S. Navy victory of the Quasi-War, USS Constellation defeats and captures the French frigate L’Insurgente off Nevis, boosting American morale and validating naval expansion efforts.
USS Constellation fights the French frigate La Vengeance in a hard-fought action off Saint Kitts; the engagement ends inconclusively, but underscores the sustained intensity of Quasi-War naval operations in the Caribbean.
American and French negotiators sign the Convention of 1800 (Treaty of Mortefontaine), ending the Quasi-War and formally unwinding the remaining obligations of the 1778 Franco-American treaties.
After ratification processes and revisions, the Convention of 1800 becomes effective, normalizing relations and conclusively closing the crisis that began with the XYZ Affair and escalated into the Quasi-War.
XYZ Affair and the Quasi-War with France (1797–1800)
