ObscureHollywood.net’s review published on Letterboxd :
Prince Valiant in the Days of King Arthur, a comic strip created in 1937, is still produced for the Sunday comic pages. In this film, Valiant, played by Robert Wagner, fights the evil Black Knight (James Mason) to save the throne of King Arthur. Wagner, young and athletic, provides a nice visual version of Valiant but his speaking voice weakens him, especially against the suave, well phrased, tones of Mason. Brian Ahern sounds and looks good as King Arthur, but Sterling Hayden, sounding like the American he was, is ridiculous as Sir Gwain. However, the plentiful action is fun to watch, and how much more can be expected of a comic strip brought to life?