What do the letters XYZ and John Adams have to do with each other? If you are not sure, do not feel bad. I have a hunch that most people have no idea as to the answer.
Wikipedia's notes that, "The XYZ Affair was a diplomatic scandal that lasted from March of 1797 to 1800. Three French agents, originally only publicly referred to as X, Y, and Z, but later revealed as Jean Conrad Hottinguer, Pierre Bellamy and Lucien Hauteval, demanded enormous concessions from the United States as a condition for continuing bilateral peace negotiations. The concessions demanded by the French included 50,000 pounds sterling, a $10 million loan from the United States, a $250,000 personal bribe to French foreign minister Charles Maurice de Talleyrand, and a formal apology for comments made by U.S. President John Adams."
By the time the affair was over, France and the USA had actually engaged in what is now called the Quasi-War. Although termed quasi, the fighting was real. The French seized over 300 American ships. The US retaliated by capturing 22 French ships off the American coast and in the West Indies.
President John Adams had to deal with the XYZ Affair during his term in office. In the XYZ Affair Speech, which he delivered on May 16th, 1797, he summarized what was happening and called on Congress to fund a navy.
Adams said, "A naval power, next to the militia, is the natural defense of the United States. The experience of the last war would be sufficient to shew that a moderate naval force, such as would be easily within the present abilities of the Union, would have been sufficient to have baffled many formidable transportations of troops from one state to another, which were then practiced. Our sea coasts, from their great extent, are more easily annoyed and more easily defended by a naval force than any other. With all the materials our country abounds; in skill our naval architects and navigators are equal to any, and commanders and sea men will not be wanting. But although the establishment of a permanent system of naval defense appears to be requisite, I am sensible it can not be formed so speedily and extensively as the present crisis demands."
The whole "quasi" conflict and diplomatic affair ended with the Convention of 1800. However, President Adams showed Europe that the new American nation was ready to defend itself and could not be bullied. The naval program Adams helped to stimulate would also help the USA defeat the Barbary pirates in the First (1801-1805) and Second Barbary War (1815) as well as aiding in the War of 1812.