Tudor line would end; the risk of civil war between rival claimants was a possibility if Elizabeth died childless. Numerous suitors from nearly all European nations sent ambassadors to English court to put forward their suit. Risk of death came dangerously close in 1564 when Elizabeth caught smallpox; when she was most at risk, she named Robert Dudley as Lord Protector in the event of her death. After her recovery, she appointed Dudley to the Privy Council and created him Earl of Leicester, in the hope that he would marry Mary, Queen of Scots. Mary rejected him, and instead married Henry Stuart, Lord Darnley, a descendant of Henry VII, giving Mary a stronger claim to the English throne. Although many Catholics were loyal to Elizabeth, many also believed that, because Elizabeth was declared illegitimate after her parents' marriage was annulled, Mary was the strongest legitimate claimant. Despite this, Elizabeth would not name Mary her heir; as she had experienced during the reign of her predecessor Mary I, the opposition could flock around the heir if they were disheartened with Elizabeth's rule. Numerous threats to the Tudor line occurred during Elizabeth's reign. In 1569, a group of Earls led by Charles Neville, the sixth Earl of Westmorland, and Thomas Percy, the seventh Earl of Northumberland attempted to depose Elizabeth and replace her with Mary, Queen of Scots. In 1571, the Protestant-turned-Catholic Thomas Howard, the fourth Duke of Norfolk, had plans to marry Mary, Queen of Scots, and then replace Elizabeth with Mary. The plot, masterminded by Roberto di Ridolfi, was discovered and Norfolk was beheaded. The next major uprising was in 1601, when Robert Devereux, the second Earl of Essex, attempted to raise the city of London against Elizabeth's government. The city of London proved unwilling to rebel; Essex and most of his co-rebels were executed. Threats also came from abroad. In 1570, Pope Pius V issued a Papal bull, Regnans in Excelsis, excommunicating Elizabeth, and releasing her subjects from their allegiance to her. Elizabeth came under pressure from Parliament to execute Mary, Queen of Scots, to prevent any further attempts to replace her; though faced with several official requests, she vacillated over the decision to execute an anointed queen. Finally, she was persuaded of Mary's (treasonous) complicity in the plotting against her, and she signed the death warrant in 1586. Mary was executed at Fotheringhay Castle on 8 February 1587,