The world has a way of undermining complex plans. This is particularly true in fast moving environments. A fast moving environment can evolve more quickly than a complex plan can be adapted to it. By the time you have adapted, the target has changed.

In war everything is simple, but it's the simple things that are difficult.

Strength of character does not consist solely in having powerful feelings, but in maintaining one's balance in spite of them.

Principles and rules are intended to provide a thinking man with a frame of reference.

War is the domain of physical exertion and suffering.

War is not merely a political act but a real political instrument, a continuation of political intercourse, a carrying out of the same by other means.

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.