©National Archives

Princess Elizabeth to Queen Mary, 16 March 1554 Elizabeth knew the terror of imprisonment and her life was in constant danger during the reign of her sister, Mary, a staunch catholic who fiercely disapproved of Elizabeth's protestant leanings. In the spring of 1554, Mary had her sister arrested on suspicion of complicity in the abortive rebellion of Sir Thomas Wyatt in protest against her forthcoming marriage to King Phillip II of Spain. Elizabeth wrote this letter to Mary, pleading her innocence and begging for her release from the Tower. Mary did not reply to the letter, but Wyatt himself eventually cleared Elizabeth of all complicity and she was therefore compelled to release her sister. Elizabeth's future remained uncertain until Mary's death in 1558 gave her the crown of England.