Sun Tzu said: There are terrains that are open, there are obstacles, there are branches, there are narrow places, there are dangers, and there are distances. I can go there and he can come. It is called Tong. Those who are Tongxing will first live in Gaoyang to benefit the grain road and fight for their benefit. You can go there, but it's hard to go back. It's called hanging. If the enemy is unprepared, he will be victorious if he goes out. If the enemy is prepared, he will be defeated if he goes out and it will be difficult to return, which is disadvantageous. It's not good for me to go out, and it's bad for him to go out. It's called a branch. In the case of branch shape, although the enemy can benefit me, I have no way to escape, so I can lure him away and make the enemy half-attack to gain advantage. If there is a pass in the shape of a pass, I will occupy it first, and I will definitely fill it up to wait for the enemy. If the enemy takes the lead, don't follow him if he is in a position to do so, or follow him if he is not in a position to do so. If there is a dangerous situation, I will occupy it first, and I will definitely stay in Gaoyang to wait for the enemy. If the enemy positions it first and lures them away, do not follow. Those who are far away will be difficult to challenge, and the battle will be disadvantageous. All these six are the way of the earth, and they cannot be ignored until they are appointed. Some soldiers are moving, some are galloping, some are trapped, some are collapsing, some are in chaos, and some are going north. All these six things are not disasters from heaven and earth, and they can be passed over. If the generals are evenly matched, if they hit ten with one blow, it is said to go away; if the soldiers are strong and the officers are weak, it is said to be galloping; if the officers are strong but the soldiers are weak, it is said to be trapped; if the big officials are angry and refuse to obey, and when the enemy confronts them, they fight on their own. If the general does not know his capabilities, it is said to collapse; Weakness and lack of strictness, unclear teachings, irregular officers and soldiers, and scattered troops are called chaos; the general cannot predict the enemy, unite with a small number, attack the strong with the weak, and the soldiers have no choice of front, which is called north. All these six factors are the way to defeat, and they cannot be ignored until they are put to the right. The terrain of the land is aided by soldiers. It is the way of a general to predict the enemy's victory and to plan the dangerous passes near and far. Those who know this and use warfare will win; those who do not know this and use warfare will lose. Therefore, if the way of war is victorious, if the Lord says there is no war, then we must fight; if the way of war is invincible, if the Lord says there must be war, there is no way to fight. Therefore, when we advance, we do not seek fame, and when we retreat, we do not avoid sin. We only protect the people, benefit the Lord, and are the treasure of the country. He regards his pawn as a baby, so he can go to the deep stream with him; he regards his pawn as his beloved son, so he can die with him. Thick but unable to control, loving but unable to command, chaotic but unable to be cured, it is like a arrogant man who cannot be used. Knowing that our soldiers can attack, but not knowing that the enemy cannot attack, is half the victory; knowing that the enemy can attack, but not knowing that our soldiers cannot attack, is half the victory; knowing that the enemy can attack, knowing that our soldiers can Attacking without knowing that the terrain is invincible is half the battle won. Therefore, those who know how to fight can move without being confused, and can move without being exhausted. Therefore it is said: If you know the enemy and yourself, victory is not in danger; if you know heaven and earth, victory is possible.

-----"Sun Tzu's Art of War Terrain Ten"