In war the chief incalculable is the human will, which manifests itself in resistance, which in turn lies in the province of tactics. Strategy has not to overcome resistance, except from nature. Its purpose is to diminish the possibility of resistance, and it seeks to fulfil this purpose by exploiting the elements of movement and surprise.
B. H. Liddell HartThe predominance of moral factors in all military decisions. On them constantly turns the issue of war and battle. In the history of war they form the more constant factors, changing only in degree, whereas the physical factors are different in almost every war and every military situation.
B. H. Liddell HartIt should be the aim of grand strategy to discover and pierce the Achilles' heel of the opposing government's power to make war. Strategy, in turn, should seek to penetrate a joint in the harness of the opposing forces. To apply one's strength where the opponent is strong weakens oneself disproportionately to the effect attained. To strike with strong effect, one must strike at weakness.
B. H. Liddell HartThe 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.
B. H. Liddell HartIn 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.
B. H. Liddell Hart