John of Gaunt of Castile. As his father and elder brother, Edward, the Black Prince, became incapacitated due to poor health, Gaunt assumed control of many government functions, and rose to become one of the most powerful political figures in England. He was faced with military difficulties abroad and political divisions at home, and disagreements as to how to deal with these crises led to tensions between Gaunt, the English Parliament, and the ruling class, making him an extremely unpopular figure for a time. John exercised great influence over the English throne during the minority of King Richard II, and the ensuing periods
Succession to Elizabeth I of England John of Gaunt, would claim the throne and so overturn the principle of primogeniture, was revived in the context of the Elizabethan succession, after seven generations. John of Gaunt's eldest daughter having married into the Portuguese House of Aviz, one of his descendants was the Infanta of Spain, Isabella Clara Eugenia. The legitimacy of Isabella's claim was seriously put forward, on the Catholic side of the argument. A reason given for Essex's Rebellion was that the Infanta's claim had gained traction with Elizabeth and her counsellors. The Succession to the Crown Act 1543 was the third such act of the