Arthur of the Britons (1972)

Arthur is the chief of a small Celt tribe in Dark Ages Britain, a century or two after the withdrawal of Rome. Arthur struggles to weave the scattered tribes of Celts, Jutes and others into a union that can effectively oppose the Saxon invaders who are arriving in Britain in growing numbers. He is aided by his adoptive father, Llud, and his foster brother, Kai, who is himself a Saxon foundling.