The book aims to provide the reader with a state-of-the-art introduction to classic and modern military theory. The text accounts for the most important theories within the field by developing and analysing these theories, as well as problematising both their normative and explanatory aims. It is a book about military theory that does not only reflect a single way of relating to knowledge of war and warfare. Indeed, it is precisely by introducing contrasting perspectives as well as constantly criticising the theories that learning is furthered. Any book that focuses on the actual theories and the concepts they are founded on will, by definition, lack large elements of the historical background that puts theories and theorists into context. This could lead to a limited understanding of the origin and aims of the theories and to discussions becoming more abstract than would otherwise have been the case. However, this approach has a proven pedagogical merit within political theory and there are no reasons to believe that it would be less advantageous for learning military theory. Moreover, the dangers of being too abstract is minimised through the use of plentiful of empirical illustrations of the theories. There are alternative ways of introducing military theory to new readers. The existing introductory literature on military theory appears too ambitious toward detail, too specialised or too practically oriented to introduce the field optimally. There is, therefore, a need for an introductory text for the entire field of military theory that focuses whole-heartedly on the theories not on their context, how they are expressed in practice in warfare or their preachers. An approach like this takes as its starting point to systematically discuss military theory on the basis of its qualities as theory and more precisely as social science theory. By developing and systematising military theory, this book can thus be said to complement and improve the existing literature. It is, however, important to point out that this book is primarily a textbook that, as a whole, only has limited aims as regards originality. For example, we do not claim that our interpretation of, for example, Clausewitz's reasoning on the nature of war is ground-breaking, but as an introductory book, its pedagogical approach, structure, analytical framework, and parts of its analysis have original features. This book will be of great interest for students of military theory, strategic studies, security studies and defence studies.