In the first chapter of Book I, the author defines war as a “duel on an extensive scale” (1). War comprises multiple duels in a single war event between two enemy sides that use “an act of violence” for the purpose of compelling “the other to submit to his will” (1). This violence “knows no bounds” (2). In this context, the violence is the means, whereas the enemy’s submission is the objective. To “disarm the enemy” is the goal achieved by placing “him in a situation which is more oppressive to him than the sacrifice which we demand” (2). Alternatively, the enemy can be overthrown. To defeat the enemy, we must “proportion our efforts to his power of resistance” (2) comprised of “the sum of available means and the strength of the will” (3). However, even after the enemy’s defeat, “the result in war is never absolute” (5).

Wars require the armed forces, the support of the country, and allies. Sometimes they can be “a completely isolated act” with no previous history (3). Overall, “the original motive for war” is the “political object” that defines military action (5). Military action must continue toward a climax unless there is cause to suspend it.