This paper is a summary of my 700-page very academic thesis, in Danish, to be published by Aarhus University Press (AUP). A shorter booklet based on it was published by AUP too (November 2014, 250 pages) and so were a number of shorter articles in English, French and German. In Luhmann’s systems theory and in sociology at large there is a missing link consisting in the lack of a sociology of war. A number of German systems theoreticians use Luhmann’s theory to fill that gap. Yet Luhmann (born 1927), who was a soldier and a prisoner of war from age 15-17, would not write a “Der Krieg der Gesellschaft”. The attempt to narrow this lacuna is indeed a heavy burden and a difficult task, in which it is decisive firstly to get the basic distinctions right about a second order observation of war as a conflict system – to be distinct from a military organisational system. This, I do by beginning with a reconceptualization of Carl von Clausewitz’ form analysis and self-description of war from Vom Kriege (1832). The central point is to observe the self-reference of war, or how war became war about war. Conflict is basically a problem of essentially contested communication. Once this historical self-reference established around the 17th century was in place, war became delimited by its structural couplings to religion, mass media (propaganda), finance, welfare for victims and veterans, law, politics and other functional systems. The costs of war increased, reconstituted and transformed modern society in a way that has formed a range of risks and – of course – neglected blind spots.