The state of crisis is the real war; the equilibrium is nothing but its reflex. - Carl von Clausewitz

The first, the supreme, the most far-reaching act of judgment that the statesman and commander have to make is to establish by that test the kind of war on which they are embarking; neither mistaking it for, nor trying to turn it into, something that is alien to its nature.

War is simply the continuation of politics by other means

Modern wars are seldom fought without hatred between nations; this serves more or less as a substitute for hatred between individuals.