This fourth, and fullest, of Abbott's volumes on Oliver Cromwell covers the last three years of his life, from the autumn of 1655 to his death in September 1658. Throughout this time he ruled as Protector, although he apparently came close to taking the crown during the "kingship crisis" of 1657, when parliament, in replacing the Instrument of Government by the more traditional constitution of the Humble Petition, demonstrated that a conservative...