I told about Louis Sixteenth that got his head cut off in France long time ago; and about his little boy the dolphin, that would a been a king, but they took and shut him up in jail, and some say he died there.

– Mark Twain

The Adventures of Huckleberry Finn, Chapter 14. Huck to Jim. This is an allusion to the execution of the French King Louis XVI and the imprisonment of the royal family during the French Revolution.