Mary of Guise died - On this day in history On 11 June 1560, Mary of Guise, mother of Mary Queen of Scots and widow of King James V, died. Mary of Guise, mother of Mary Queen of Scots and widow of King James V of Scotland, died on 11 June 1560, of dropsy. Mary acted as regent during her daughter Mary's childhood and it was she who arranged her marriage to the dauphin of France. Mary of Guise became ill whilst attempting to fortify Edinburgh Castle against an English assault.