King Arthur, or Artus, king of the Celts, contrary to today's depiction of having been a hero or the like, was absolutely not a courtly king in shining armor, nor a good-hearted and noble hero. King Artus was a fierce sixth-century clan leader, a 'war king', who led his pagan warriors in bloody battles and raids. He was a slaughterer and kept the name the 'Boar of Cornwall'. His 'knights' truly were bloodthirsty murderous thugs as you say. Artus himself was Merlin's protege, a pupil of Merlin the druid, for seven years.