Sibling rivalry and political intrigue are a dangerous combination. In the case of George Plantagenet, Duke of Clarence, mixing the two brought about his early demise. As a young man, Clarence joined in a rebellion against his brother, King Edward IV. He soon had a change of heart and reconciled with Edward, but a few years later, he became involved in another plot against him. Clarence was then sent to the Tower of London, where he was secretly executed, allegedly by being drowned in what? Discuss