The invention of gunpowder and the constant improvement of firearms are enough in themselves to show that the advance of civilization has done nothing practical to alter or deflect the impulse to destroy the enemy, which is central to the very idea of war.
Carl von ClausewitzIn 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.
Carl von ClausewitzThe more a general is accustomed to place heavy demands on his soldiers, the more he can depend on their response.
Carl von Clausewitz