"War is a mere continuation of policy by other means" - Carl von Clausewitz
"Political power grows out of the barrel of a gun" - Mao Zedong
Critical War Studies is a budding field in social sciences that seeks to understand the human phenomena of war. It's primarily studied from the perspective of International Relations, but also incorporates elements of critical theory, gender theory, post-colonialism etc, as well as traditional theories of strategy and tactics.
I'll dump a mix of pdfs and links to articles that was used in a course I took on the subject. In general, the content deals with the topics of "What is War", "How are humans affected by War", and/or critiques of modern and "post-modern" warfare. Frequently mentioned is Carl von Clausewitz, Michel Foucault, Deleuze & Guattari, and Jean Baudrillard.
I'll start of with some chapters from the defining work "On War" by Clausewitz, in which we find the genesis of the important friction between Perfect and Real war, i.e. war as we desire it to be and war as it actually plays out, a distinction that becomes important in the analysis of so called post-modern warfare.
http://www.clausewitz.com/readings/OnWar1873/BK1ch01.html
http://www.clausewitz.com/readings/OnWar1873/BK1ch07.html#a
http://www.clausewitz.com/readings/OnWar1873/BK8ch06.html#B