It is the nature of war that what is beneficial to you is detrimental to the enemy and what is of service to him always hurts you. It is therefore a maxim never to do, or to omit doing, anything as a consequence of his actions, but to consult invariably your own interest only. And you depart from this interest whenever you imitate such measures as he pursues for his benefit. For the same reason, it would be wrong for him to follow such steps as you take for your advantage. (General Maxims)

No plan survives contact with the enemy

“No battle plan survives first contact with the enemy.” Not when the enemy is me.

In practice we always base our preparations against an enemy on the assumption that his plans are good; indeed, it is right to rest our hopes not on a belief in his blunders, but on the soundness of our provisions. Nor ought we to believe that there is much difference between man and man, but to think that the superiority lies with him who is reared in the severest school.

One should attend to one's enemies, for they are the first persons to detect one's errors.

To prevent the enemy from fathoming one’s intentions is of the first importance.

Plans made without allowance for the intentions of the enemy are liable to miscarry. So it was to prove in 1916.

In conformity with all that has been said on the subject up to the present, two fundamental principles reign throughout the whole plan of the war, and serve as a guide for everything else.

The first is: to reduce the weight of the enemy’s power into as few centres of gravity as possible, into one if it can be done; again, to confine the attack against these centres of force to as few principal undertakings as possible, to one if possible; lastly, to keep all secondary undertakings as subordinate as possible. In a word, the first principle is, to act concentrated as much as possible.

The second principle runs thus to act as swiftly as possible; therefore, to allow of no delay or detour without sufficient reason.

No matter how sound a tactical plan may be, the chances of successful execution will be greatly increased if you have first secured the willing acceptance by commander responsible for execution of the missions you plan to assign them. Ensure that they receive notice of your decision and the principal details of your plan as approved in ample time to permit them and their subordinates to make their necessary reconnaissance and issue their orders.

[Regarding the 'Advance to Contact'] The simple truth about war is that if you are on the attack, you can't do a damned thing until you find your enemy, and the only way to do that is to push on, at whatever speed seems prudent, until you see or hear him, or he makes his presence known by letting fly at you.

No plan survives first contact with the enemy.

Pay attention to your enemies, for they are the first to discover your mistakes.

Success in warfare is gained by carefully accommodating ourselves to the enemy's purpose.

Even if you seek to harm an enemy,
You should remove your own defects and cultivate good qualities.
Through that you will help yourself,
And the enemy will be displeased.