An unofficial war between the US and France, the Quasi War was sparked by the XYZ Affair and the decision of the United States to terminate its treaties with France. Consisting of a series of conflicts at sea, the war ended with the signing of the Convention of 1800, which allowed for the end of the previous alliance between the US and France but asserted a “firm, inviolable, and universal peace, and a true and sincere Friendship between” the two countries.