Edward VI died on 6 July 1553. Lady Jane was declared
queen on 10 July. The duchess joined her for the proclamation and during her stay in the Tower. She had been fetched when Northumberland realised Jane's confusion and overwhelming feelings, and she managed to calm her daughter down. Since she had seen the king himself and spoken to him about the succession, she could convince Jane that she was the rightful queen and heir. Their success was short-lived. Jane was deposed by armed support in favour of Mary I on 19 July 1553. The
Duke of Suffolk was arrested, but released days later thanks to the duchess's intervention. The moment she heard of her husband's arrest, she rode over to Mary in the middle of the night to plead for her family. Despite all odds, not only did the duchess manage to be received by the queen, but also could secure him a pardon by placing all the blame on Northumberland. While in his household, Lady Jane had fallen sick of food poisoning and had suspected Northumberland's family. The duchess now used her daughter's suspicions and her husband's sickness to accuse Northumberland of having tried to kill her family. Therefore, Mary was willing to pardon the Duke of Suffolk. She intended to pardon Jane once her coronation was complete, sparing the 16-year-old's life. However,
Wyatt the Younger declared a revolt against Mary on 25 January 1554. The Duke of Suffolk joined the rebellion, but was captured by
Francis Hastings, 2nd Earl of Huntingdon. The revolt had failed by February. The plot ringleaders had wished to supplant Mary with her half-sister Elizabeth, although Elizabeth played no part in the matter. After the attempt to put Jane on the throne Frances was confined in the
Tower of London for a time. ==Second marriage and death==