The XYZ affair was an unsuccessful diplomatic mission that contributed to hostilities between the U.S. and France at the end of the 18th century. In 1793, a war broke out between Great Britain and France. Both countries wanted the support of the U.S., but the 1794 Jay Treaty was so favorable to Britain's trading industry that the French decided to retaliate.
The French began capturing American ships on the seas. While President John Adams started preparing for war against France, he also authorized a diplomatic mission to try to smooth out relations between the two countries. In 1797, Talleyrand, the Foreign Minister, would not receive the American diplomats and sent liaisons instead. They asked for a significant loan and a bribe for Talleyrand. The French delegates also urged Adams to renounce his negative speech against France, and they wanted the U.S. to release the French government from responsibility in the seizing of American ships.
These demands were not well received by the Americans. By 1798, Adams told Congress that the mission was failing and the U.S. must continue to prepare for war. However, many members of Congress felt uninformed and wanted Adams to release all the letters the American diplomats had sent. Adams agreed, but he removed the names of the French intermediaries, replacing them with the letters W, X, Y and Z. A congressional commission was established to negotiate with France. This action eventually resulted in the Convention of 1800, which Congress ratified in 1801.