In any problem where an opposing force exists and cannot be regulated, one must foresee and provide for alternative courses. Adaptability is the law which governs survival in war as in life ... To be practical, any plan must take account of the enemy's power to frustrate it; the best chance of overcoming such obstruction is to have a plan that can be easily varied to fit the circumstances met.

The blurring of the line between policy and strategy] encouraged soldiers to make the preposterous claim that policy should be subservient to their conduct of operations, and (especially in democratic countries) it drew the statesman on to overstep the definite border of his sphere and interfere with his military employees in the actual use of their tools.

Direct experience is inherently too limited to form an adequate foundation either for theory or for application. At the best it produces an atmosphere that is of value in drying and hardening the structure of thought. The greater value of indirect experience lies in its greater variety and extent. History is universal experience, the experience not of another, but of many others under manifold conditions.

If you find your opponent in a strong position costly to force, you should leave him a line of retreat as the quickest way of loosening his resistance. It should, equally, be a principle of policy, especially in war, to provide your opponent with a ladder by which he can climb down.

If we clear the air of the fog of catchwords which surround the conduct of war, and grasp that in the human will lies the source and mainspring of all conflict, as of all other activities of man's life, it becomes clear that our object in war can only be attained by the subjugation of the opposing will. All acts, such as defeat in the field, propaganda, blockade, diplomacy, or attack on the centres of government and population, are seen to be but means to that end.

The most dangerous error is failure to recognize our own tendency to error.

For even the best of peace training is more theoretical than practical experience ... indirect practical experience may be the more valuable because infinitely wider.