It has often been overlooked that sociology was founded in times and societies where war and the military were common affairs. Therefore it is not surprising that sociology has a lot to say about these impactful phenomena. This, however, has not always been acknowledged in the history of this discipline, even though military sociology as a subdiscipline has matured since WWII. This article points at the possibility of presenting an overview of classical sociology’s significance for the study of the armed forces, especially in questions that are of a substantive rational nature. The case of Georg Simmel is presented as an example; it appears that the sociological study of the armed forces and their actions can profit from the insights of this sociologist with respect to: positions and numbers in networks; conflict dynamics; secrecy and trust; and the position of the stranger. At the end, the article advocates the development of a sociology that studies the more operational side of the armed forces, taking the interests of all people who are involved in conflicts into account.