Arthur of Brittany, born in 1187, was the son of Geoffrey Duke of Brittany and Constance, daughter of Conan of Brittany. The couple had two children, Arthur and Eleanor, also called the Pearl of Brittany for her great beauty.Through his father then, Arthur was the grandson of Henry II and Eleanor of Aquitaine.

When Richard the Lion-Heart, King Richard I of England, signed the treaty of Messina, he agreed to have Arthur, his nephew, marry the daughter of Tancred of Lecce, the ruler of Sicily. At this point- perhaps to give the boy some cachet, or because he truly believed in representative succession which would have the son of his next youngest brother take precedence over John- he made the thirteen year old boy his heir. This naturally infuriated John, who of course wanted the crown to be his, and it prompted him to betray his brother and King. The marriage never took place, because the next we hear Arthur, by then Duke of Richmond, was betrothed to Mary of France. When Richard died suddenly, his mother Eleanor of Aquitaine supported John's claim to the throne.

Arthur's Breton supporters then revolted, backed by Philip II of France, who was then at war with John. John and Philip shared a complex political history, and after Philip won most of John's posessions, he gave them to Arthur, further infuriating King Johm (perhaps that was his intention!)

In order to use her as a pawn in this Kingmaker game, Arthur captured his grandmother Eleanor of Aquitaine, but John did manage to rescue her. In 1202, at Mirabeau, Arthur himself was captured by John, and imprisoned in the Castle of Falaise. He was subsequently removed to Rouen, and never seen again. His sister, the Pearl, was also imprisoned, but treated gently, for the rest of her life.

So what happened to Arthur? According to Agnes Strickland, William de Braose, John's friend and ally, and the man who had taken Arthur at Mirabeau, was the commander at Rouen. Eight years after Arthur had been taken, he fell into disfavor, for no apparent reason. The Welsh monks at Margam wrote a chronicle, and it thought that the information came directly from the de Braoses, who were patrons of the Cistercian Abbey that housed the monks. The Chronicle claimed that on the third of April, in the year 1203, John was at Rouen, and ate his dinner. He got drunk and 'possessed of the devil and slew him with his own hand and tying a heavy stone to the body, cast it into the Seine.' Later sources claimed that he had sadistically blinded the 16 year old boy before murdering him.

Did he murder him, or give the order? Most probably, though it is also possible Arthur died of natural causes, but if this had been the case, it would have possibly served John's interests better to have shown the body, and given it a proper burial. Although we shrink from any sort of justification of murder, and are especially horrified when blood murders blood, we must remember the times and not inflict thirteenth century characters with our presend day sensibilities. None of Henry II's boys were especially sentimental when it came to blood relations; they had, after all, all rebelled against their father. John, who was his father's favorite, had done no less. To hold the crown, one did what one had to do, nephew or no nephew, and Arthur alive was always going to be the liability he had already proven himself to be. So, yes, it is likely that John did kill him, but it is also likely that if the shoe had been on the other foot, John would have been the victim.