The object of defense is preservation; and since it is easier to hold ground than to take it, defense is easier than attack. But defense has a passive purpose: preservation; and attack a positive one: conquest.... If defense is the stronger form of war, yet has a negative object, it follows that it should be used only so long as weakness compels, and be abandoned as soon as we are strong enough to pursue a positive object.

Surprise becomes effective when we suddenly face the enemy at one point with far more troops than he expected. This type of numerical superiority is quite distinct from numerical superiority in general: it is the most powerful medium in the art of war.

War is an act of force, and to the application of that force there is no limit. Each of the adversaries forces the hand of the other, and a reciprocal action results which in theory can have no limit.

To be practical, any plan must take account of the enemy's power to frustrate it.

Two qualities are indispensable: first, an intellect that, even in the darkest hour, retains some glimmerings of the inner light which leads to truth; and second, the courage to follow this faint light wherever it may lead.

In War, the young soldier is very apt to regard unusual fatigues as the consquence of faults, mistakes, and embarrassment in the conduct of the whole, and to become distressed and depondent as a consequence. This would not happen if he had been prepared for this beforehand by exercises in peace.

Friction is the only concept that more or less corresponds to the factors that distinguish real war from war on paper.