This disambiguation page is incorrect; it claims that there have been only three Prince Arthurs. However, there is one more Prince Arthur, the grandson of Henry II through his son Geoffrey. If King John (of Robin Hood fame) had not murdered him, he actually should have claimed the throne, as his father had a better claim than John, according to the inheritance system of primogeniture. One thing is clear: it is unlucky to be a Prince of the Realm named Arthur.