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. When a chieftain is fighting in his own territory, it is dispersive ground. When he has penetrated into hostile territory, but to no great distance, it is facile ground. Ground the possession of which imports great advantage to either side, is contentious ground. Ground on which each side has liberty of movement is open ground. 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. 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. Mountain forests, rugged steeps, marshes and fens—all country that is hard to traverse: this is difficult ground. 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. Ground on which we can only be saved from destruction by fighting without delay, is desperate ground. On dispersive ground, therefore, fight not. On facile ground, halt not. On contentious ground, attack not. On open ground, do not try to block the enemy’s way. On ground of intersecting highways, join hands with your allies. On serious ground, gather in plunder. In difficult ground, keep steadily on the march. On hemmed-in ground, resort to stratagem. For it is the soldier’s disposition to offer an obstinate resistance when surrounded, to fight hard when he cannot help himself, and to obey promptly when he has fallen into danger. We cannot enter into alliance with neighbouring princes until we are acquainted with their designs. We are not fit to lead an army on the march unless we are familiar with the face of the country—its mountains and forests, its pitfalls and precipices, its marshes and swamps. We shall be unable to turn natural advantages to account unless we make use of local guides. To be ignorant of any one of the following four or five principles does not befit a warlike prince. When a warlike prince attacks a powerful state, his generalship shows itself in preventing the concentration of the enemy’s forces. He overawes his opponents, and their allies are prevented from joining against him. Hence he does not strive to ally himself with all and sundry, nor does he foster the power of other states. He carries out his own secret designs, keeping his antagonists in awe. Thus he is able to capture their cities and overthrow their kingdoms. Bestow rewards without regard to rule, issue orders without regard to previous arrangements; and you will be able to handle a whole army as though you had to do with but a single man. Confront your soldiers with the deed itself; never let them know your design. When the outlook is bright, bring it before their eyes; but tell them nothing when the situation is gloomy. Place your army in deadly peril, and it will survive; plunge it into desperate straits, and it will come off in safety. For it is precisely when a force has fallen into harm’s way that is capable of striking a blow for victory. Success in warfare is gained by carefully accommodating ourselves to the enemy’s purpose. By persistently hanging on the enemy’s flank, we shall succeed in the long run in killing the commander-in-chief. This is called ability to accomplish a thing by sheer cunning. On the day that you take up your command, block the frontier passes, destroy the official tallies, and stop the passage of all emissaries. Be stern in the council-chamber, so that you may control the situation. If the enemy leaves a door open, you must rush in. Forestall your opponent by seizing what he holds dear, and subtly contrive to time his arrival on the ground. Walk in the path defined by rule, and accommodate yourself to the enemy until you can fight a decisive battle. At first, then, exhibit the coyness of a maiden, until the enemy gives you an opening; afterwards emulate the rapidity of a running hare, and it will be too late for the enemy to oppose you.