If we consider the actual basis of this information [i.e., intelligence], how unreliable and transient it is, we soon realize that war is a flimsy structure that can easily collapse and bury us in its ruins. ... Many intelligence reports in war are contradictory; even more are false, and most are uncertain. This is true of all intelligence but even more so in the heat of battle, where such reports tend to contradict and cancel each other out. In short, most intelligence is false, and the effect of fear is to multiply lies and inaccuracies.
Carl von ClausewitzAs each man's strength gives out, as it no longer responds to his will, the inertia of the whole gradually comes to rest on the commander's will alone. The ardor of his spirit must rekindle the flame of purpose in all others; his inward fire must revive their hope.
Carl von ClausewitzIf you entrench yourself behind strong fortifications, you compel the enemy seek a solution elsewhere.
Carl von ClausewitzEverything 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.
Carl von Clausewitz