War is only caused through the political intercourse of governments and nations - war is nothing but a continuation of political intercourse with an admixture of other means.

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

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.

[The cause of inaction in war] ... is the imperfection of human perception and judgment which is more pronounced in war than anywhere else. We hardly know accurately our own situation at any particular moment while the enemy's, which is concealed from us, must be deduced from very little evidence.

We must evaluate the political sympathies of other states and the effect war may have on them. To assess these things in all their ramifications and diversity is plainly a colossal task. Rapid and correct appraisal of them clearly calls for the intuition of a genius; to master all this complex mass by sheer methodical examination is obviously impossible. Bonaparte was quite right when he said that Newton himself would quail before the algebraic problems it could pose.

The general unreliability of all information presents a special problem in war: all action takes place, so to speak, in the twilight, which, like fog or moonlight, often tends to make things seem grotesque and larger than they really are. Whatever is hidden from full view in this feeble light has to be guessed at by talent, or simply left to chance. So once again for the lack of objective knowledge, one has to trust to talent or to luck.

The deduction of effect from cause is often blocked by some insuperable extrinsic obstacle: the true causes may be quite unknown. Nowhere in life is this so common as in war, where the facts are seldom fully known and the underlying motives even less so.

The difficulty of accurate recognition constitutes one of the most serious sources of friction in war, by making things appear entirely different from what one had expected.

Everything in war is very simple, but the simplest thing is difficult. The difficulties accumulate and end by producing a kind of friction that is inconceivable unless one has experienced war. ... Countless minor incidents - the kind you can never really foresee - combine to lower the general level of performance, so that one always falls short of the intended goal. ...