The novel’s depiction of John Felton is fairly accurate. Felton was a Puritan and a lieutenant in the English army who stabbed the Duke of Buckingham to death on August 23, 1628. In the novel, Felton’s intense religious fanaticism is given a new direction as Milady spins a classic Gothic tale of horror for her jailer, who immediately repents of his role in persecuting her. Buckingham was not at all popular with the Puritans, and in the novel, Milady uses this fact to her advantage.
Historically, the real John Felton stabbed the Duke for two reasons. First of all, he believed that he was doing England a favor by getting rid of such an unpopular man. Secondly he was enraged by the fact that he had been denied a promotion. In the novel, Felton gives this second reason when questioned about his motives by Lord de Winter, but we are meant to understand that the evil Milady was behind the whole affair. More than anyone else, the character of John Felton illustrates Dumas’s skillful blend of fact and fiction.