In what century did Twain write the postscript for A Connecticut Yankee in King Arthur's Court, and is this tale fictional or true?
The story certainly is a tall tale. As much as I'd love to time travel, we haven't discovered how to do it yet.
There are actually two postscripts in this book. The first was written by Clarence, who says that he has had to write the end to the Yankee's story. During their final battle with the knights, the Yankee is stabbed and near death. Clarence and the others take him into a cave, where Merlin, disguised as an old woman pretending to help care for him, gives him a sleeping potion. Unmasking himself, Merlin exclaims:
"Ye were conquerors; ye are conquered! These others are perishing --you also. Ye shall all die in this place--every one--except him. He sleepeth now--and shall sleep thirteen centuries. I am Merlin!"
After writing his postscript, Clarence hides it with the sleeping man.
The second postscript begins with "Final P.S. by M.T." Twain wants us to believe that he found the sleeping man and brought him to wherever Twain is staying. Since the book was published in 1889, we are to believe that Merlin's plan succeeded and that the Yankee only just awakened in the 19th century.