King John is reputed to be the worst of England s kings. Before his death in 1216, his desperate exploitation of his subjects for ever more money had turned him into the mythical monster of Hollywood legendeven though the fictional Robin Hood was invented much later. In contrast to his brother Richard, he appeared incompetent in battle, failing to defend Normandy in 1202-04, and was unsuccessful in recovering his lost lands in 1214. King John s unpopularity...