Based on the provided text: What was the "X.Y.Z. fever"?

Context: The XYZ Affair was a political and diplomatic episode in 1797 and 1798, early in the presidency of John Adams, involving a confrontation between the United States and Republican France that led to the Quasi-War. The name derives from the substitution of the letters X, Y, and Z for the names of French diplomats Jean-Conrad Hottinguer, Pierre Bellamy, and Lucien Hauteval in documents released by the Adams administration.

Answer: The XYZ Affair was a political and diplomatic episode in 1797 and 1798 involving a confrontation between the United States and Republican France that led to the Quasi-War.