A Connecticut Yankee in King Arthur's Court (1921)
A Connecticut Yankee in King Arthur's Court is a 1921 American silent film adaptation of Mark Twain's 1889 novel A Connecticut Yankee in King Arthur's Court. The film was produced by the Fox Film Corporation (later 20th Century Fox) and directed by Emmett J. Flynn based on a screenplay by Bernard McConville. It is notable as the first film adaptation of Twain's novel and as the first film about time travel to the past.
More at Wikipedia.