John Boorman's Excalibur (1981) remains the best film ever made about the King Arthur legend. It now has an equal Antoine Fuqua's King Arthur (2004) except that this one largely dispenses with the mythic Arthur, with all its medieval embellishments, and concentrates on the historical foundations in post-Roman Britain. The Roman imperial government withdrew its legions and administrators from their far-flung province of Britannia in A.D. 407. Germanic tribes were threatening the heart of the empire (Italy), and all available forces were necessary for its defense. Roman civilization and culture did not vanish from Britannia, nor did her people cheer the departure of Roman forces. The Romano-British were a wealthy and civilized people; many were Christian; and they were now alone.Warlike tribes from north of Hadrian's Wall (the Picts) and from the western island of Hibernia (the Scotti, the Irish) had long coveted their lands, launched raids, and attempted to colonize the western fringes of the province. And within a few decades, they were threatened by an even more formidable foe Saxon invaders from northern Germany. Nevertheless, the Britons managed to hold back these various voracious tribes for over a century, and consequently Romano-Celtic Britain survived as a distinct political society and culture until late in the sixth century.
One of their most effective military leaders was Lucius Artorius Castus (Arthur in Brythonic, the language of the Celtic Britons), a Romano-British cavalry officer whose family had resided in the island since the late second century. Arthur's elite armoured cavalry defeated the Saxons in twelve engagements, culminating in the decisive battle of Badon Hill (A.D. 493), which won for his people a forty year respite of relative peace and safety the probable origin of the mythic age of Camelot. 
Ignore the critics who have panned this film. From the reviews I have read, most of those who have done so, know nothing of the history of the period, and have misinterpreted their own confusion and bewilderment as products of a weak script, rather than their own ignorance.  In addition, many of them are, frankly, politically correct commissars who regard Kill Bill (2004) as a great work of art but The Passion (2004) as excessively violent and anti-Semitic. Any film that seeks not to vilify the western past but to honor it, in all its complexity and magnificence, is sure to incur their ire. The film is gorgeous, moving, and conveys a realistic sense of fifth century Roman Britain.
David Franzoni's screenplay is quite good (he wrote the screenplay for Gladiator). He keeps his story true to the larger historical narrative, while only altering and compressing some details necessary poetic license to find a smaller story that can stand for the whole enormous scope of the history. The story begins as the Romans are withdrawing from the island. Arthur (Clive Owen) is a Roman officer, commanding a small contingent of elite Sarmatian cavalry, with whom he has formed a tight bond; they are nearing the end of a twelve-year period of service to the empire, after which they plan on returning to their native land, in what is now Hungary. These are honor-bound men, who will keep their word and fulfill their oath of service to the very end. 
Arthur himself plans on moving to Rome. Although he is of mixed parentage his father a Roman and mother a Briton he sees himself primarily as Roman. This will change. Gradually, Arthur comes to identify with the land in which he was born and with his mother's people, who seem more honorable than the rather decadent and deceitful Roman officials and aristocrats. The most decisive influence on him is Guinevere (Keira Knightley), a beautiful female Celtic warrior who is unwaveringly devoted to her people. Her first words to Artorius are devastating: u201CArthur, the Briton who kills his own people.u201D She respects his abilities, knows he is an honorable and humane man, and believes he can be won over to their side. After he describes to her the glories of Rome (perhaps hoping she will go with him), she replies: u201CI belong to this land,u201D meaning she will never leave it, no matter how luxurious life may be in Rome. In the end, Arthur decides to remain in Britain to fight off the invading Saxons, who are pouring in to colonize the island; and his Sarmatian knights, adoptive Britons now, join him. He makes common cause with his old foe Merlin, Guinevere's father.  After their combined forces crush the Saxons, in a beautifully choreographed battle scene, Arthur marries Guinevere and is anointed king of his people, the Celtic Britons. Marvelous.
Readers of a paleolibertarian persuasion can find much to love here. This glimpse of the last days of the Roman Empire gives us hope that the American empire will some day experience the same deserved fate. In addition, we see that the collapse of Roman political authority is not followed by anarchy and bedlam, as neocons and other statists would predict, but by the resurgence of the native Britons, the elevation of their natural leaders Arthur, Merlin, and the restoration of a natural social order, based on ethno-cultural kinship and common consent.  Were the United States to fall apart, we can be confident that the disjointed fragments will sort themselves out in a similar way.
 For those interested in the fascinating history of this age, see P.F.J. Turner's The Real King Arthur: A History of Post-Roman Britannia, A.D. 410A.D. 593 (1993).
 See, for instance, the review by Joe Williams in the St. Louis Post Dispatch and Roger Ebert in the Chicago Sun-Times; both available online through the movie review search engine, mrqe.com.
 After defeating the Sarmatians in A.D. 175, the Emperor Marcus Aurelius dispatched some heavy Sarmatian cavalry to Britannia; their lives were spared in return for life-long service to Rome.
 In the film, the native Britons are known as u201CWoads,u201D after their habit of painting their skin with blue dye from the Woad plant, and they are depicted as residing north of Hadrian's Wall, in what is now Scotland. That would make them Picts, who actually made common cause with the Saxons against Arthur and his Britons. But again, the film need not be truthful in every detail to be truthful in the larger telling.
 We cannot help noticing too that if Arthur had been a radical individualist and solipsist, concerned only with enjoying his rights and maximizing his comfort and possessions, he would have returned to Rome; but then there would have no heroism, no legend, and no movie.
July 26, 2004