Regency England was a pivotal time of political uncertainty, with a changing monarchy, the Napoleonic Wars, and a population explosion in London. In Susanna Clarke’s fantasy novel Jonathan Strange and Mr. Norrell, the era is also witness to the unexpected return of magic. Locating the consequences of this eruption of magical unreason within the context of England’s imperial history, this study examines Merlin and his legacy, the roles of magicians throughout history, the mythology of disenchantment, the racism at work in the character of Stephen Black, the meaning behind the fantasy of magic’s return, and the Englishness of English magic itself. Looking at the larger historical context of magic and its links to colonialism, the book offers both a fuller understanding of the ethical visions underlying Clarke’s groundbreaking novel of madness intertwined with magic, while challenging readers to rethink connections among national identity, rationality, and power.