John de Vere, 13th Earl of Oxford, seized and held it during a siege of 23 weeks against 6,000 of Edward IV's troops in 1473–74. Perkin Warbeck, a pretender to the English throne, occupied the Mount in 1497. Sir Humphrey Arundell, Governor of St Michael's Mount, led the Prayer Book Rebellion of 1549. During the reign of Queen Elizabeth I, it was given to Robert Cecil, Earl of Salisbury, by whose son it was sold to Sir Francis Bassett. During the Civil War, Sir Arthur Bassett, brother of Sir Francis, held the Mount against the Parliament until July 1646.