“The most robust defense of historical counterfactuals to date . . . For those interested in this fascinating subject, Black’s book is indispensable.”—Publishers Weekly (starred review) What if there had been no World War I or no Russian Revolution? What if Napoleon had won at Waterloo in 1815, or if Martin Luther had not nailed his complaints to the church door at Wittenberg in 1517, or if the South had won the American Civil War? The questioning of apparent certainties or “known knowns” can be fascinating and, indeed, “What if?” books are very popular. However, this speculative approach, known as counterfactualism, has had limited impact in academic histories, historiography, and the teaching of historical methods. In this book, Jeremy Black offers a short guide to the subject, one that is designed to argue its value as a tool for public and academia alike. He “demonstrates that, in skillful hands, counterfactual history is more than just fun; as one ingredient among many, it can be an extremely fertile source of explanation” (History Today). “[Black’s] illustrative examples of ‘what if' ‘how,’ and ‘why’ will make readers sit back and wonder.”—Kirkus Reviews “With a unique methodology, Black performs a what-if analysis of history to show how little it takes to change the world’s fate . . . This book provokes thought and speculation while also entertaining.”—Foreword Reviews “A sparkling defense of the legitimacy and utility of counterfactual history―of what ifs―and the best single work on its subject available.”—Weekly Standard