This is the first wide-ranging analysis of Alain Badiou's use, development and transformation of the concept of history. Despite the wealth of perspectives now available on how social and cultural practices take shape, historicism still appears to be the most dominant. The Militant Historian examines this primacy and reveals how Badiou's work offers a radical riposte. Exploring key texts in Badiou's oeuvre and how his philosophical ideas disrupt dominant conceptions of history and the role of the historian, Kerry William Purcell addresses how these ideas could transform our approaches to the historical and what it means to 'do history' as a meaningful endeavour. Adopting a chronological approach to Badiou's work, each chapter explores specific conceptual developments in his writing and how they lend themselves to a reconsideration of the subject who speaks history. From these new and disruptive modes of doing emerges the figure of the militant historian - a role with the potential to impact how we practice history outside the narrow strictures of academic life.