28. If we know that the enemy is open to attack, but are unaware that our own men are not in a condition to attack, we have gone only halfway towards victory. 29. If we know that the enemy is open to attack, and also know that our men are in a condition to attack, but are unaware that the nature of the ground makes fighting impracticable, we have still gone only halfway towards victory. 30. Hence the experienced soldier, once in motion, is never bewildered; once he has broken camp, he is never at a loss. 31. Hence the saying: If you know the enemy and know yourself, your victory will not stand in doubt; if you know Heaven and know Earth, you may make your victory complete. XI. THE NINE SITUATIONS 1. Sun Tzŭ said: The art of war recognises nine varieties of ground: (1) Dispersive ground; (2) facile ground; (3) contentious ground; (4) open ground; (5) ground of intersecting highways; (6) serious ground; (7) difficult ground; (8) hemmed-in ground; (9) desperate ground. 2. When a chieftain is fighting in his own territory, it is dispersive ground. 3. When he has penetrated into hostile territory, but to no great distance, it is facile ground. 4. Ground the possession of which imports great advantage to either side, is contentious ground. 5. Ground on which each side has liberty of movement is open ground. 6. Ground which forms the key to three contiguous states, so that he who occupies it first has most of the Empire at his command, is ground of intersecting highways. 7. When an army has penetrated into the heart of a hostile country, leaving a number of fortified cities in its rear, it is serious ground. 8. Mountain forests, rugged steeps, marshes and fens—all country that is hard to traverse: this is difficult ground. 9. Ground which is reached through narrow gorges, and from which we can only retire by tortuous paths, so that a small number of the enemy would suffice to crush a large body of our men: this is hemmed in ground. 10. Ground on which we can only be saved from destruction by fighting without delay, is desperate ground. 11. On dispersive ground, therefore, fight not. On facile ground, halt not. On contentious ground, attack not. 12. On open ground, do not try to block the enemy’s way. On ground of intersecting highways, join hands with your allies. 13. On serious ground, gather in plunder. In difficult ground, keep steadily on the march. 14. On hemmed-in ground, resort to stratagem. On desperate ground, fight. 15. Those who were called skilful leaders of old knew how to drive a wedge between the enemy’s front and rear; to prevent co-operation between his large and small divisions; to hinder the good troops from rescuing the bad, the officers from rallying their men. 16. When the enemy’s men were scattered, they prevented them from concentrating; even when their forces were united, they managed to keep them in disorder.