Before closing this chapter we may be allowed to remark that Richard III, when he had his nephews murdered in the Tower of London, in 1483, came legitimately by his cruel nature. John Lackland was the progenitor of all the Plantagenets who succeeded him on the English throne, and, like his direct descendant, Richard Crookback, was a usurper, because Prince Arthur, son of his elder brother, Geoffrey Plantagenet, was lineal heir to the throne. History and tradition agree in saying that John caused Prince Arthur to be murdered, and some historians say that he was the actual murderer. He was the only coward of his race, and was, also, frivolous and deliberately ill-mannered. When on a visit to Ireland, in the supposed interest of his father, he caused a revolt among the Irish chiefs who called upon him, by pulling their long beards and otherwise insulting them. Those cringing chiefs deserved the treatment they received, but John Lackland, as he was dubbed, is not, therefore, excusable for having acted toward them as a boor and a ruffian. Later on, when he became King of England, he again visited Ireland, and built many strong castles. That of Limerick, called King John’s Castle, is still almost perfectly preserved, and is a superb relic of Norman military architecture. As the Irish were not provided with armament, or appliances, for making a successful siege, the fortresses built by King John were, so far as they were concerned, virtually impregnable. Whenever the Normans were vanquished in the field, they retired to their castles, which were amply provisioned, and defied the vengeance of their foes.