QuasiWar

The Quasi-War was an undeclared naval conflict between the United States and the French Republic that lasted from 1798 to 1800. It occurred largely in the Caribbean and western Atlantic as both nations sought to protect or attack shipping in the wake of the French Revolutionary era and strained Franco-American relations after the XYZ Affair and the perception that the United States had aligned with Britain through the Jay Treaty. The fighting was primarily naval, involving battles between frigates, privateers, and merchantmen rather than a full-scale war.

Background tensions grew after the French Revolution and the collapse of the 1778 treaty alliance with the United States. The XYZ Affair in 1797–1798 provoked American anger toward France and led Congress to authorize a reorganization and expansion of the U.S. Navy. The conflict saw frequent naval escorts, convoy operations, and ship-to-ship engagements rather than large land campaigns. The United States built a temporary but capable navy of frigates and squadrons; the French relied on privateers and regular naval units operating in Caribbean lanes.

Notable actions included the engagement of the USS Constellation with the French frigate L’Insurgente in 1799, a decisive American victory that helped establish morale and Naval credibility for the young United States. The war also featured numerous encounters and seizures of merchant ships by both sides as economic warfare intensified.

The Quasi-War ended with the Convention of 1800, also known as the Treaty of Mortefontaine, which reestablished peace and neutralized naval hostilities without a formal declaration of war. The conflict contributed to a strengthened U.S. Navy and set a precedent for undeclared naval conflicts that would recur in later years.