•Why it earns a slot
The most influential work of military theory ever written, and the source of the idea, still cited by policymakers and generals alike, that war is fundamentally a political tool rather than a separate domain with its own rules.
Clausewitz, a Prussian general who fought against Napoleon, spent his final years writing an unfinished theory of war grounded in his own combat experience rather than abstract rules. His core claim is that war is not a separate, self-contained activity governed by its own logic, it is politics continued by other means, and every military decision has to be understood in that political context.
This distillation is written from the freely available original, which is always the better read when you have the time: Project Gutenberg.