When Duke Edmund of Cornwall betrays King Arthur in favor of the Saxons and pins it on the outlaw Robert Marshall, Robert flees Camelot with Arthur's daughter Katherine, the rightful heir to the throne. Will they find Merlin and discover a way to overthrow the usurper before they are captured or killed?
Siege of the Saxons provides examples of:
- Adapted Out: Arthur, Excalibur, Camelot, Merlin, and a Saxon invasion force are the only elements of the Arthurian stories used, the rest is nowhere to be seen.
- Anachronism Stew: As is not uncommon with Arthurian adaptations, the look of the movie is distinctly more modern than it ought to be. Notably enough Arthur uses Henry IV's coat of arms, historically not used until almost a millennium after Arthur is supposed to have lived.
- Color-Coded Armies: Conveniently, the final battle is between Pendragon-loyal forces in blue and Saxon invaders in red.
- Excalibur in the Stone: Excalibur is identified with the sword Arthur drew from the stone, making only the rightful ruler able to draw it from its scabbard.
- False Flag Operation: Edmund dresses his soldiers up as Saxons (while also being allied to the actual Saxons) so that people won't suspect he was the one who overthrew Arthur.
- The High Queen: Katherine is expected to succeed Arthur and become Queen Regnant of England. Once she draws Excalibur the lords of England recognize her as their queen, and she proudly accepts the responsibility.
- Lovable Rogue: Robert is an outlaw and not quite noble enough to be Just Like Robin Hood (willing to rob the king, not too keen on the "giving to the poor" idea), and opposes Edmund at first mostly just because he framed him, but by the end he's willing to risk his life for queen and country.
- Magical Realism: Other than the enchantment on Excalibur and the existence of Merlin, it's pretty much a (ignoring the anachronisms) realistic knight film like many of its time.
- No Name Given: The only credited characters other than Katherine, Robert, Edmund, Merlin, and Arthur are "The Limping Man" (Edmund's henchman), "The Blacksmith", "The Doctor", and "Young Monk". Nobody else (including the Saxon prince) even makes it into the credits.
- Not His Sled: You might expect Arthur to meet his end fighting Mordred at Camlann. Nope, he's killed off for real early on by Edmund's fake Saxons.
- Only the Chosen May Wield: Excalibur can only be drawn from its scabbard by the rightful ruler of England. This is used to reveal Edmund as illegitimate and prove Katherine is who she claims to be.
- Rewarded as a Traitor Deserves: The priest who alerts Edmund's forces that Katherine is in the church is run down by them as soon as they get there.
- Sweet Polly Oliver: Robert cuts Kate's hair and dresses her in loose-fitting peasant clothes so that he can pass her off as his mute brother.
- You Have Outlived Your Usefulness: The Saxons have no incentive to keep Edmund alive after he's exposed as a traitor, and their prince kills him on the spot.