When both sides can come and go, the terrain is said to be easily passable. When the terrain is easily passable, take up your position first, choosing the high and sunny side, convenient to supply routes, for advantage in battle.
When you can go but have a hard time getting back, you are said to be hung up. On this type of terrain, if the opponent is unprepared, you will prevail if you go forth, but if the enemy is prepared, if you go forth and do not prevail you will have a hard time getting back, to your disadvantage.
When it is disadvantageous for either side to go forth, it is called standoff terrain. On standoff terrain, even though the opponent offers you an advantage, you do not go for it -- you withdraw, inducing the enemy half out, and then you attack, to your advantage.
On narrow terrain, if you are there first, you should fill it up to await the opponent. If the opponent is there first, do not pursue if the opponent fills the narrows. Pursue if the opponent does not fill the narrows.
On steep terrain, if you are there first, you should occupy the high and sunny side to await the opponent. If the opponent is there first, withdraw from there and do not pursue.
On wide-open terrain, the force of momentum is equalized, and it is hard to make a challenge, disadvantageous to fight.
Understanding these six kinds of terrain is the highest responsibility of
the general, and it is imperative to examine them.
So among military forces there are those who rush, those who tarry, those who fall, those who crumble, those who riot, and those who get beaten. These are not natural disasters, but faults of the generals.
Those who have equal momentum but strike ten with one are in a rush. Those
whose soldiers are strong but whose officers are weak tarry. Those whose
officers are strong but whose soldiers are weak fall. When colonels are
angry and obstreperous, and fight on their own out of spite when they meet
opponents, and the generals do not know their abilities, they crumble.
When the generals are weak and lack authority, instructions are not clear,
officers and soldiers lack consistency, and they form battle lines every
which way, this is riot. When the generals cannot assess opponents, clash
with much greater numbers or more powerful forces, and do not sort out the
levels of skill among their own troops, these are the ones who get beaten.
These six are ways to defeat. Understanding this is the ultimate
responsibility of the generals; they must be examined.
The contour of the land is an aid to an army; sizing up opponents to determine victory, assessing dangers and distances, is the proper course of action for military leaders. Those who do battle knowing these will win, those who do battle without knowing these will lose.
Therefore, when the laws of war indicate certain victory it is surely
appropriate to do battle, even if the government says there is to be no
battle. If the laws of war do not indicate victory, it is appropriate not
to do battle, even if the government orders war. Thus one advances without
seeking glory, retreats without avoiding blame, only protecting people, to
the benefit of the government as well, thus rendering valuable service to
the nation.
Look upon your soldiers as you do infants, and they willingly go into deep valleys with you; look upon your soldiers as beloved children, and they willingly die with you.