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.
Carl von Clausewitz...as man under pressure tends to give in to physical and intellectual weakness, only great strength of will can lead to the objective.
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 Clausewitz