These are the words of Master Sun:
We have now arrived at the question of billeting the army and surveying the enemy.
When you do reconnaissance and when you move into position, you should pass quickly over mountain ranges and keep close to valleys. Make camp on sunny hills. Do not climb great heights seeking battle. These are the rules of mountain warfare.
When crossing a river, you should not stay near its banks. Do not attack an army when it is midstream crossing a river. It is better to let half of the enemy army cross and then attack. If you seek to attack, you should not do so while you are on the banks of a river. It is always best to be upstream of the enemy. These are the rules of river warfare.
When crossing swamps and marshes, your only concern should be to leave the areas as quickly as possible. If you are forced to fight in a swamp or a marsh, you will need to make sure that you have grass and water nearby and a cluster of trees behind you. These are the rules of swamp and marsh warfare.
In a level and dry area, you should adopt a position where the ground slopes upwards on your right flank and on your rear. Then danger will come from the front, and safety will lie behind you. These are the rules of warfare on level terrain.
These are the rules of warfare, which the Yellow Emperor [a mythological figure thought to be the first ruler of a unified China] used to defeat the four emperors.
An army should seek high ground as opposed to low ground, and sunny places instead of shadowy ones. If you want to avoid diseases, you should make camp on dry and firm ground. This will help you attain victory. When you arrive at a hill or on the bank of a river, you should always make sure to occupy the sunny side and let your right flank face the hill or the river. Positioning yourself in this manner will allow the terrain to aid you and give your army an advantage.
If, due to heavy rain somewhere inland, a river is foaming and rushing by more quickly than normal, you should wait until the water has returned to its normal levels before you cross the river.
Avoid areas with steep cliffs, rapid torrents, deep natural caves, restricted spaces, tangled thickets, bogs, and chasms. Leave such dangerous places quickly, but seek to lure the enemy into such places. When we face such places, the enemy should have his back to them.
If impassable terrain - dams with reeds and rushes, water basins, and hilly forests with thick undergrowth - is near to where you have camped, you should put out patrols, as men will lie in ambush in such places, and forward scouts sent by the enemy will spy on you from such places, if you let them.
When the enemy is near but passive and patient, it is a sign that he feels safe and secure in the natural advantages of his position. When the enemy keeps his distance while attempting to provoke a battle, he is trying to make you move. If he is camped in advantageous terrain, he will try to bait you into coming to him.
Movement among trees is a sign that the enemy is moving closer. When the enemy puts up screens in the thick grass, he is trying to confuse us. Groups of birds that suddenly take flight are signs of an ambush. Animals fleeing herald an attack.
When a column of dust rises from the ground, it is a sign that the chariots of the enemy are moving in on you. When a large cloud of dust clings to the earth, it is a sign that the foot soldiers of the enemy are moving in on you. When the cloud of dust seems to be travelling in many different directions, the soldiers of the enemy are collecting firewood. A dust cloud that seems to move this way and then that way is a sign that the enemy is making camp.
If the envoys of the enemy speak meekly and humbly while the army of the enemy is preparing for battle, you can expect that his army will soon advance on you. Threats and feints are a sign that the enemy will soon retreat. When the light chariots are brought forward and take up position on the flanks of the enemy's army, he is preparing for battle.
Offerings of peace unaccompanied by affirmed and sworn agreements are the signs of a ruse.
If soldiers can be seen running to fall into rank, the pivotal moment draws near. When only a part of the enemy's army advances while another part retreats, it is an attempt to bait you into attacking. When the enemy's soldiers can be seen leaning against their spears, it is a sign that they are weakened by hunger. If the men who are tasked with bringing water to the enemy's troops drink before the troops they are supposed to serve, it is a sign that the enemy is running out of water. If the enemy has a clear advantage but fails to press it, it is a sign that his troops are exhausted. If birds gather in an area, it is a sign that the enemy does not occupy that area. Unrest in the enemy's camp at night is a sign of agitation and nervousness. General unrest in the enemy's camp is a sign that the authority of the enemy commander is weak. A constant movement of banners and flags is a sign that a mutiny may be about to unfold. If the officers of the enemy are prone to anger, it is a sign that the troops are worn down.
When an army feeds its horses grain and slaughters its cattle, and when its troops do not hang their pots over the campfire, you are being shown that they do not intend to return to their tents and are ready to fight to the death.
The sight of little groups of men speaking in hushed voices is a sign of dissatisfaction in the ranks of the army. If the enemy gives out rewards too frequently, it is a sign that the enemy has almost used up his resources. If the enemy hands out too many punishments, it is a sign of mounting distress.
If the enemy's officers use violence against the rank and file and afterwards appears to be afraid of those that they have punished, it is a sign that the discipline of the army has unraveled.
When the enemy's envoys are sent bearing compliments, it is a sign that the enemy desires a truce. If the enemy angrily lines up for battle but refrains from attacking and retreating, you must take great care to study him closely. If you make light of the enemy, you are sure to find yourself captured by him.
When soldiers are punished before they have grown loyal to you, they will not follow your commands, and if they will not follow your commands, they are useless to you. Conversely, it is also true that soldiers who are never punished after they have become loyal to you will become useless to you. Soldiers should be treated humanely first and foremost, but must also be subjected to control and discipline. This is the path to victory. When soldiers in training are conditioned to follow commands given to them, the army is well-disciplined. If they are not trained in this manner, the discipline of the army will suffer. A commander should trust his troops, but also always insist that his commands are followed. In the end this will serve not only the commander, but also his troops.