King Arthur: Legend of the Sword

Mordred, an iron-fisted warlock, and his armies lay siege to Camelot, seeking to establish the dominance of mages over humankind. Uther Pendragon, king of the Britons, infiltrates Mordred's lair and beheads him, saving Camelot. Uther's treacherous younger brother Vortigern, who covets the throne, orchestrates a coup and sacrifices his wife Elsa to moat hags to become a demon knight, who kills Uther's wife Igraine and slays Uther in combat. The only survivor is Uther's son Arthur, who drifts away in a boat and ends up in Londinium, where he is found and raised by prostitutes.