The more usual reason for adopting a strategy of limited aim is that of awaiting a change in the balance of force ... The essential condition of such a strategy is that the drain on him should be disproportionately greater than on oneself.

With growing experience, all skillful commanders sought to profit by the power of the defensive, even when on the offensive.

While there are many causes for which a state goes to war, its fundamental object can be epitomized as that of ensuring the continuance of its policy - in face of the determination of the opposing state to pursue a contrary policy. In the human will lies the source and mainspring of conflict.

The art of the indirect approach can only be mastered, and its full scope appreciated, by study of and reflection upon the whole history of war. But we can at least crystallize the lessons into two simple maxims- one negative, the other positive. The first is that, in face of the overwhelming evidence of history, no general is justified in launching his troops to a direct attack upon an enemy firmly in position. The second, that instead of seeking to upset the enemy's equilibrium by one's attack, it must be upset before a real attack is, or can be successfully launched

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

Direct pressure always tends to harden and consolidate the resistance of an opponent.

Air forces offered the possibility of striking a the enemy's economic and moral centres without having first to achieve 'the destruction of the enemy's main forces on the battlefield'. Air-power might attain a direct end by indirect means - hopping over opposition instead of overthrowing it.