1797-1800: XYZ Affair - After French diplomats demanded bribes from American diplomats in order for them to negotiate a treaty, the United States took offense and terminated all treaties with France. This resulted in an unofficial war with France during which a series of conflicts at sea occurred that soured the Franco-American relationship for a time before a reset of relations in 1800. (jan 1, 1797 – jan 1, 1800)