Invincibility is in oneself, and vulnerability is in the opponent. Invincibility is a matter of defense, vulnerability is a matter of attack. Therefore skillful warriors are able to be invincible, but they cannot cause opponents to be vulnerable. That is why it is said that victory is discerned and not manufactured.
Those who do not know the plans of competitors cannot prepare alliances. Those who do not know the lay of the land cannot maneuver their forces. Those who do not use local guides cannot take advantage of the ground.
If you are situated at a great distance from the enemy, and the strength of the two armies is equal, it is not easy to provoke a battle, and fighting will be to your disadvantage.
Therefore the skillful leader subdues the enemy's troops without any fighting; he captures their cities without laying siege to them; he overthrows their kingdom without lengthy operations in the field.