This volume is the result of an academic initiative organized by the Center for International Historical Studies of the University of Barcelona (CEHI-UB) in April 2012, with the purpose of bringing Military History to the center of the attention of university and historiographical debate. This choice is based on the idea that, too often, Military History is considered a technical discipline, only intended for experts. On the contrary, we think that - on the one hand - this research field constitutes an unavoidable tool for the interpretation of the historical processes of contemporaneity, and that - on the other - Military History is among the most interesting research fields because of its intrinsic interdisciplinarity. On the basis of these considerations, the congress and the resulting book propose the analysis of some of the main war processes of the twentieth century, from a perspective that could situate them in the wider background defined by the conflicts themselves. The book gathers the contributions of Professors Fortunato Minniti (University of Roma Tre, Rome), Giuseppe Conti (University La Sapienza, Rome), Joan Villarroya (University of Barcelona), Allan R.Millett (University of New Orleans) and Antoni Segura i Mas (University of Barcelona), respectively about World War I, war intelligence, the Spanish Civil War, World War II, and the asymmetric conflicts ranging from the Cold War to more recent examples.