The kings in playing cards were designated by the French card designers in the 16th century to represent great kings. Which one named is incorrect?

King of Diamonds represented Roman Caesar Augustus, while other sources say it was Julius Caesar. It certainly was not Louis XII of France, known as the 'father of the people'.

Playing cards arrived in Europe in the late 14th century, and decks differed greatly depending on where they were produced. There were inconsistent numbers of cards and design, although all decks had suits made up of court cards (now usually called face cards) and numbered cards. Eventually, as card-playing in Europe became more widespread, the decks were mass-produced with stencils and always included 52 cards, the same number that a deck includes now.

It was the French card-makers in the late 16th century who standardized the suits of spades, hearts, diamonds, and clubs and designated the four kings as David, Alexander, Charlemagne, and Caesar Augustus (some sources say the king of diamonds is Julius Caesar, not Augustus). This designation was ended in the late 18th century and from then on, the kings in decks of cards have represented no specific person, any more than the kings on a chessboard stand for illustrious royals of the past.