[Literally, "get the advantage of the ground," which means not only securing good positions, but availing oneself of natural advantages in every possible way. Chang Yu says: "Every kind of ground is characterized by certain natural features, and also gives scope for a certain variability of plan. How it is possible to turn these natural features to account unless topographical knowledge is supplemented by versatility of mind?"] 6. So, the student of war who is unversed in the art of war of varying his plans, even though he be acquainted with the Five Advantages, will fail to make the best use of his men. [Chia Lin tells us that these imply five obvious and generally advantageous lines of action, namely: "if a certain road is short, it must be followed; if an army is isolated, it must be attacked; if a town is in a parlous condition, it must be besieged; if a position can be stormed, it must be attempted; and if consistent with military operations, the ruler’s commands must be obeyed." But there are circumstances which sometimes forbid a general to use these advantages. For instance, "a certain road may be the shortest way for him, but if he knows that it abounds in natural obstacles, or that the enemy has laid an ambush on it, he will not follow that road. A hostile force may be open to attack, but if he knows that it is hard-pressed and likely to fight with desperation, he will refrain from striking," and so on.] 7. Hence in the wise leader’s plans, considerations of advantage and of disadvantage will be blended together. ["Whether in an advantageous position or a disadvantageous one," says Ts’ao Kung, "the opposite state should be always present to your mind."] 8. If our expectation of advantage be tempered in this way, we may succeed in accomplishing the essential part of our schemes. [Tu Mu says: "If we wish to wrest an advantage from the enemy, we must not fix our minds on that alone, but allow for the possibility of the enemy also doing some harm to us, and let this enter as a factor into our calculations."] 9. If, on the other hand, in the midst of difficulties we are always ready to seize an advantage, we may extricate ourselves from misfortune. [Tu Mu says: "If I wish to extricate myself from a dangerous position, I must consider not only the enemy’s ability to injure me, but also my own ability to gain an advantage over the enemy. If in my counsels these two considerations are properly blended, I shall succeed in liberating myself…. For instance; if I am surrounded by the enemy and only think of effecting an escape, the nervelessness of my policy will incite my adversary to pursue and crush me; it would be far better to encourage my men to deliver a bold counter-attack, and use the advantage thus gained to free myself from the enemy’s toils." See the story of Ts’ao Ts’ao, VII. § 35, note.] 10. Reduce the hostile chiefs by inflicting damage on them;