The book contains contributions from mathematicians, historians of mathematics, historians of military and war, military analysts and philosophers from eight countries (Denmark, Germany, Japan, Norway, Russia, Sweden, United Kingdom, USA), who took part in the “International Meeting on Mathematics and War” (Blekinge Institute of Technology, Karlskrona, Sweden, 2002). The main aim of the book is to give a picture of the interaction between mathematics, war and weapons. Contributions show the role played by military support in the development of modern mathematics and in the careers of some mathematicians (in particular, during the World War II), as well as parts of mathematics important for the war and military industry (e.g., coding machines, optimal control, mathematical modeling). Some chapters contain a discussion on how mathematics influenced the character and performance of modern warfare, weapons and the military industry. The authors also describe difficult individual decisions of certain mathematicians during the war time (including N. Bohr, A.N. Kolmogorov, M. Rees, A. Turing and K. Ogura) and their personal histories. It leads to a discussion of many general ethical questions. The book can be recommended to mathematicians, historians of mathematics and military, as well as to readers interested in ethics, sociology and political sciences.