This musical adaptation of the Tony Award winning musical play (of the same name) by Alan Jay Lerner, from T.H. White’s "The Once and Future King", was directed by Joshua Logan. It earned three Academy Awards – for Art Direction-Set Decoration, Costume Design, and Music, Scoring of Music, Adaptation or Treatment – in addition to Oscar nominations for Cinematography and Sound. However, its lead actors: Richard Harris as King Arthur, Vanessa Redgrave as Guenevere, Franco Nero as Sir Lancelot, and David Hemmings as Mordred leave something to be desired (acting-wise, but especially singing when) compared to the original production’s Richard Burton, Julie Andrews, Robert Goulet, Roddy McDowall (respectively). Among those also in the film’s cast are: Lionel Jeffries as King Pellinore, Laurence Naismith as Merlyn, and Estelle Winwood as Lady Clarinda.
Arthur, who as a boy was the only one able to remove the sword (Excalibur) from a stone in which it was ‘stuck’, a sign that he was the one true King of England, was mentored by Merlyn as he grew into the role. He meets and establishes flirtatious ‘relations’ with Guenevere, who’s desperate for adventure, before he & she realize that their marriage had already been arranged.
Arthur’s idea for bringing together the various warring provinces of his country involves establishing a coalition of representative knights that would meet in his castle at a round table (so that no one could claim its head, e.g. prime position of power) of equals. France’s invincible Lancelot Du Lac hears of the “Knights of the Round Table” and decides that he too must serve Arthur. But the religious and somewhat arrogant about both his ability and purity Lancelot is destined to fall in love with Guenevere.
When Arthur realizes this, and subsequently suspects that his queen is having an affair with his “right hand”, he decides not to publicly acknowledge it – “there’s no proof” (e.g. for a court of law, an instrument that the forward-thinking King himself first devised) – for what he thinks is an honorable reason (to save his kingdom). Instead of having them arrested burned at the stake, he banishes anyone (including his knights) that claims there is an affair. Of course, this erodes the nobleness of the kingdom, and its end is just a matter of time ... especially when the King’s own illegitimate son Mordred returns to England and spins his treachery.