This chapter offers an introduction to military history. It outlines the relation between history in general and the subdiscipline of military history. Traditionally military history has been “war-centric” and during the late nineteenth and early twentieth century a significant split occurred between military professionals who studied the past in order to find military lessons and establish principles of war and civilian academics who increasingly came to see military history as methodologically primitive and war-glorifying. Contemporary military history, however, has to some extent bridged this gap, and today military history is “a broad church” characterized by a rich variety of approaches. Nevertheless, a number of profound challenges face historians wanting to do military history, including commercialization of the field, a strong tendency to Euro-Atlantic centrism, lack of representation, and a paucity of theoretical and methodological debates. Currently the most notable principal approaches to military history are operational military history, war and society (new military history), deconstructivist military history, and memory culture oriented military history.