SUN ZI said:  Generally, when an army takes up a position and sizes up the enemy situation, it should pay attention to the following:

    When crossing the mountains, be sure to stay in the neighbourhood of valleys; when encamping,  select high ground facing the sunny side;  when high ground is occupied by the enemy, do not ascend to attack. So much for taking up a position in mountains.

    After crossing a river, you should get far away from it.  When an advancing invader crosses a river, do not meet him in midstream. It is advantageous to allow half his force to get across and then strike.  If you wish to fight a battle, yeu should not go to meet the invader near a river which he has to cross.  When encamping in the riverine area, take a position on high ground facing the sun. Do not take a position at the lower reaches of the enemy.  This relates to positions near a river.

    In crossing salt marshes, your sole concern should be to get over them quickly, without any delay.  If you encounter the enemy in a salt marsh, you should take position close to grass and water with trees to your rear.  This has to do with taking up a position in salt marshes.

    On level ground,  take up an accessible position and deploy your main flanks on high grounds with front lower than the back. This is how to take up a position on level ground.

    These are principles for encamping in the four situations named. By employing them,  the Yellow  Emperor conquered his four neighbouring sovereigns.

    Generally, in battle and manoeuvering, all armies prefer high ground to low and sunny  places to shady.  If an army encamps close to water and grass with adequate supplies, it will be free from countless diseases and this will spell victory. When you come to hills, dikes, or embankments, occupy the sunny side, with your main flank at the back. All these methods are advantageous to the army and can exploit the possibilities the ground offers. When heavy rain falls in the upper reaches of a river and foaming water descends, do not ford and wait until it subsides.  When encountering 'Precipitous Torrents', 'Heavenly Wells', 'Heavenly Prison', 'Heavenly Net',  'Heavenly Trap',  and  'Heavenly Cracks',  you must march speedily away from them.  Do not approach them. While we keep a distance from them we should draw the enemy toward them.  We face them and cause the eaemy to put his back to them. If in the neighbourhood of your camp there are dangerous defiles or ponds and lowlying ground' overgrown with aquatic grass and reeds, or forested mountains with dense tangled undergrowth, they must be thoroughly searched,  for these are possible places where ambushes are laid and spies are hidden.

    When the enemy is close at hand and remains quiet, he is relying on a favourable position.  When he challenges battle from afar, he wishes to lure you to advance; when he is on easy ground, he must be in an advantageous position.  When the trees are seen to move, it means the enemy is advancing; when many screens have been placed in the undergrowth, it is for the purpose of deception. The rising of birds in their flight is the sign of an ambuscade. Startled beasts indicate that a sudden attack is forthcoming.

    Dust spurting upwards in high straight columns indicates the approach of chariots.  When it hangs low and is widespread,  it betokens that infantry is approaching.  When it branches out in different directions,  it shows that parties have been seat out to collect firewood.  A few clouds of dust moving to and fro signify that the army is camping.

    When the enemy's envoys speak  in humble terms,  but the army continues preparations, that means it will advance.  When their language is strong and the enemy pretentiously drives forward, these may be signs that he will retreat.  When light chariots first go out and take positions on the wings, it is a sign that the enemy is forming for battle. When the enemy is not in dire straits but asks for a truce, he must be plotting. When his troops march speedily and parade in formations, he is expecting to fight a decisive battle on a fixed date. When half his force advances and half retreats, he is attempting to decoy you. When his troops lean on their weapons, they are famished. When drawers of water drink before carrying it to camp, his troops are suffering from thirst. When the enemy sees an advantage but does not advance to seize it, he is fatigued. When birds gather above his camp sites, they are unoccupied. When at night the enemy's camp is clamorous, it betokens nervousness. If there is disturbance in the camp, the general's authority is weak. If the banners and flags are shifted about, sedition is afoot,  lf the officers are angry, it means that men are weary. When the enemy feeds his horses  with grain, kills the beasts of burden for food and packs up the utensils used for drawing water, he shows no intention to return to his tents and is determined to fight to the death.  When the general speaks in meek and subservient tone to his subordinates, he has lost the support of his men. Too frequent rewards indicate that the general is at the end of his resources;  too frequent punishments indicate that he is in dire distress.  If the officers  at first treat the men violently and later are fearful of them, it shows supreme lack of intelligence.When envoys are sent with compliments in their mouths, it is a sign that the enemy wishes for a truce.  When the enemy's  troops march up angrily and remain facing yours for a long time, neither joining battle nor withdrawing, the situation demands great vigilance and thorough investigation.

    In war, numbers alone confer no advantage.  If one does not advance by force recklessly, and is able to concentrate his millitary power through a correct assessment of the enemy situation and enjoys full support of his men, that would suffice. He who lacks foresight and underestimates his enemy will surety be captured by him.

    If troops are punished before th.ey have grown attached to you. they will be disobedient.  If not obedient, it is difficult to employ them.  If troops have become attached to you, but  discipline is not enforced, you cannot employ them either.  Thus, soldiers must be treated in the first instance with humanity, but kept under control by iron discipline.  In this way,  the allegiance of soldiers is assured.  If orders are consistently carried out and the troops are strictly supervised, they will be obedient.  If orders are never carried out, they will be disobedient.  And the smooth implementation of orders reflects harmonious relationship between the commander and his troops.