The Art of War

Sunzi said: Warfare is a nation’s great undertaking, the ground of life and death, the way to survival or destruction. It must be carefully examined. Therefore, assess it by means of five factors, compare it by means of seven calculations, and thereby determine the true situation. The first is the Way, the second Heaven, the third Earth, the fourth the commander, and the fifth organization.

The Way causes the people to share the same purpose as their ruler, so that they may die with him, live with him, and fear no danger. Heaven means darkness and light, cold and heat, and the constraints of the seasons. Earth means high and low ground, far and near, difficult and easy terrain, broad and narrow ground, and places of death and life. The commander means wisdom, trustworthiness, benevolence, courage, and strictness. Organization means the division and regulation of forces, the chain of command, and the control of expenditures. Every commander has heard of these five factors. Those who understand them will win; those who do not will not win. Therefore, compare the sides by means of seven calculations and thereby determine the true situation: Which ruler possesses the Way? Which commander is more capable? Which side has the advantages of Heaven and Earth? Which side carries out its laws and orders? Which army is stronger? Which officers and soldiers are better trained? Which side’s rewards and punishments are clearer? From these, I know victory and defeat.

If a commander listens to my calculations, employing him will certainly bring victory, so retain him. If a commander does not listen to my calculations, employing him will certainly bring defeat, so dismiss him. Once the advantages of my calculations have been heard, create a strategic advantage to support them from outside. Strategic advantage means controlling the balance of circumstances in accordance with what is advantageous. Warfare is the way of deception. Therefore, when capable, appear incapable; when employing forces, appear inactive; when near, appear far away; when far away, appear near. Lure the enemy with profit; take him when he is in disorder; prepare against him when he is substantial; avoid him when he is strong. If he is irritable, provoke him; if he is humble, make him arrogant; if he is rested, wear him down; if his forces are united, divide them. Attack where he is unprepared; emerge where he does not expect you. These are the military strategist’s means of victory, and they cannot be disclosed in advance.

Those who, before battle, calculate victory in the ancestral temple have obtained many favorable calculations. Those who, before battle, calculate that they will not win have obtained few favorable calculations. Many calculations bring victory; few calculations do not bring victory. How much less can one win with no calculations at all? By observing the matter in this way, victory and defeat become apparent.

Sunzi said: As a general rule for employing an army, if there are a thousand swift four-horse chariots, a thousand leather-covered chariots, a hundred thousand armored troops, and provisions transported a thousand miles, then the expenses at home and in the field, the costs of entertaining envoys and advisers, materials such as glue and lacquer, and the maintenance of chariots and armor will amount to a thousand pieces of gold a day. Only then can an army of a hundred thousand be mobilized. When such an army is used in battle, what matters is swift victory. If the campaign is prolonged, weapons grow dull and ardor is blunted. If cities are attacked, strength is exhausted. If an army remains in the field for long, the state’s resources become inadequate. Once weapons are dull, ardor blunted, strength exhausted, and wealth depleted, the other lords will take advantage of this weakness and rise against you. Even if you have wise advisers, they will be unable to make the outcome favorable. Thus, in warfare we have heard of clumsy haste, but we have never seen skillful delay. There has never been a prolonged war that benefited a state. Therefore, one who does not fully understand the harms of employing an army cannot fully understand the advantages of employing an army.

Those skilled in employing an army do not levy troops a second time and do not transport provisions a third time. They obtain equipment from their own state but take provisions from the enemy; therefore, the army can have sufficient food.

A state is impoverished by its army when supplies must be transported far away. When supplies are transported far away, the common people become poor. Near an army, prices rise; when prices rise, the common people’s wealth is exhausted. When their wealth is exhausted, they are pressed by levies and labor service. With strength exhausted and wealth depleted, households within the heartland are left empty. Seven-tenths of the people’s resources are lost. Of the public resources, broken chariots, worn-out horses, armor and helmets, arrows and crossbows, halberds and shields, protective mantlets, draft oxen, and heavy wagons consume six-tenths.

Therefore, a wise commander makes every effort to feed his army from the enemy. One measure of the enemy’s grain is equivalent to twenty of ours, and one measure of his bean stalks and straw is equivalent to twenty of ours.

Therefore, what makes soldiers kill the enemy is anger; what makes them seize advantage from the enemy is material reward. Thus, in chariot fighting, when ten or more chariots are captured, reward the first to capture one, replace the enemy’s banners and flags, mix the captured chariots with your own and use them, and treat captured soldiers well and care for them. This is called defeating the enemy and becoming stronger.

Therefore, warfare values victory, not prolonged operations. Thus, a commander who understands warfare is the arbiter of the people’s lives and the master of the state’s security or danger.

Sunzi said: As a general rule for employing an army, preserving an enemy state intact is best; destroying it is second best. Preserving an enemy army intact is best; destroying it is second best. Preserving an enemy brigade intact is best; destroying it is second best. Preserving an enemy battalion intact is best; destroying it is second best. Preserving an enemy squad intact is best; destroying it is second best. Therefore, winning a hundred victories in a hundred battles is not the best of the best. Subduing the enemy’s army without battle is the best of the best.

Therefore, the highest form of warfare is to attack the enemy’s plans; next is to attack his alliances; next is to attack his army; and the lowest is to attack his cities. The method of attacking cities should be used only when unavoidable. Preparing large shields and siege wagons and assembling equipment and weapons takes three months to complete; building earthworks against the walls takes another three months. If the commander cannot control his anger and sends his men swarming up the walls like ants, a third of the officers and soldiers may be killed without the city being taken. This is the disaster of attacking cities.

Therefore, one skilled in employing an army subdues the enemy’s army without battle, takes the enemy’s cities without assault, and destroys the enemy’s state without prolonged operations. He must contend for all under Heaven while preserving it intact. Thus, his army is not worn down, and his gains can be kept complete. This is the method of attacking by strategy.

Therefore, the method of employing an army is this: if ten times the enemy’s strength, surround him; if five times his strength, attack him; if twice his strength, divide him; if equal in strength, be able to fight him; if fewer, be able to defend against him; if greatly inferior, be able to avoid him. Therefore, a small force that stubbornly resists will be captured by a larger force.

The commander is the state’s supporting pillar. If the support is complete, the state will certainly be strong; if there are gaps in the support, the state will certainly be weak.

There are three ways a ruler brings trouble upon his army. Not knowing that the army cannot advance, he orders it to advance; not knowing that the army cannot retreat, he orders it to retreat. This is called tying up the army. Not understanding the affairs of the armed forces, he interferes in their administration, and the officers and soldiers become confused. Not understanding the flexible exercise of military authority, he interferes in military appointments, and the officers and soldiers become doubtful. Once the armed forces are confused and doubtful, trouble from the other lords will arrive. This is called throwing the army into disorder and giving victory away.

Therefore, there are five ways to know victory. One who knows when battle is possible and when it is not will win. One who understands how to use both large and small forces will win. One whose superiors and subordinates share the same purpose will win. One who is prepared and waits for an unprepared enemy will win. One whose commander is capable and is not constrained by the ruler will win. These five are the way to know victory.

Therefore it is said: Know the enemy and know yourself, and you will not be imperiled in a hundred battles. If you do not know the enemy but know yourself, you will win one and lose one. If you know neither the enemy nor yourself, you will be imperiled in every battle.

Sunzi said: Those skilled in warfare in ancient times first made themselves invincible and then waited for the enemy to become vulnerable. Invincibility lies with oneself; vulnerability lies with the enemy. Therefore, those skilled in warfare can make themselves invincible, but they cannot make the enemy certain to become vulnerable. Thus it is said: Victory can be known, but it cannot always be forced.

Invincibility lies in defense; vulnerability lies in attack. One defends when strength is insufficient and attacks when strength is more than sufficient. Those skilled in defense hide beneath the deepest layers of the earth; those skilled in attack move above the highest reaches of Heaven. Thus, they can preserve themselves and achieve complete victory.

Foreseeing a victory no better than the ordinary person can foresee is not the best of the best. Winning a battle so that all under Heaven praise your skill is not the best of the best. Lifting an autumn hair does not show great strength; seeing the sun and moon does not show keen eyesight; hearing thunder does not show sharp hearing.

Those whom ancient people called skilled in warfare won victories over enemies who were easy to defeat. Therefore, the victories of those skilled in warfare bring neither a reputation for wisdom nor credit for courage. Their victories in battle are never mistaken. They are never mistaken because whatever measures they take are certain to win: they conquer an enemy who is already defeated. Therefore, those skilled in warfare establish themselves on ground where they cannot be defeated and do not miss the moment when the enemy can be defeated. Thus, a victorious army first wins and then seeks battle; a defeated army first fights and then seeks victory. Those skilled in employing an army cultivate the Way and preserve organization, and therefore can control victory and defeat.

The method of warfare has five stages: first, measurement; second, estimation of capacity; third, calculation of numbers; fourth, weighing relative strength; and fifth, victory. Ground gives rise to measurement; measurement gives rise to estimation of capacity; estimation of capacity gives rise to calculation of numbers; calculation of numbers gives rise to weighing relative strength; weighing relative strength gives rise to victory. Thus, a victorious army is like weighing a heavy measure against a tiny grain, while a defeated army is like weighing a tiny grain against a heavy measure. When the victor sends his men into battle, it is like releasing pent-up water into a gorge a thousand fathoms deep. This is disposition.

Sunzi said: In general, managing many troops is like managing few; it is a matter of divisions and numbers. Fighting with many troops is like fighting with few; it is a matter of signals and commands. To ensure that the entire army can withstand the enemy’s attack without defeat is a matter of conventional and extraordinary forces. For the army’s blow to be like a whetstone hurled against an egg is a matter of emptiness and solidity.

In every battle, engage the enemy with conventional forces and win with extraordinary forces. Therefore, one skilled at producing extraordinary maneuvers is as inexhaustible as Heaven and Earth and as unending as rivers and seas. Ending and beginning again is like the sun and moon. Dying and being born again is like the four seasons. There are no more than five musical notes, yet the variations of the five notes can never all be heard. There are no more than five colors, yet the variations of the five colors can never all be seen. There are no more than five flavors, yet the variations of the five flavors can never all be tasted. In battle, there are no more than conventional and extraordinary forces, yet the variations of conventional and extraordinary forces can never be exhausted. Conventional and extraordinary forces produce each other like a circle with no beginning or end. Who can exhaust their possibilities?

The rush of torrential water that can carry stones along is strategic force. The swift strike of a bird of prey that can crush its victim is timing. Therefore, one skilled in warfare builds an overwhelming strategic force and releases it with compressed timing. Strategic force is like a drawn crossbow; timing is like releasing its trigger.

Amid turbulence and confusion, the battle seems chaotic, yet cannot be thrown into disorder. Amid indistinct and formless movement, the disposition is rounded and cannot be defeated. Apparent disorder arises from good order; apparent cowardice arises from courage; apparent weakness arises from strength. Order and disorder are matters of organization; courage and cowardice are matters of strategic force; strength and weakness are matters of disposition.

Therefore, one skilled at moving the enemy presents a disposition that the enemy is certain to follow; he offers something that the enemy is certain to take. He moves the enemy with profit and waits for him with troops.

Therefore, one skilled in warfare seeks victory from strategic force and does not demand it from individual men. He can therefore select men and let strategic force carry them. One who relies on strategic force uses his men in battle like rolling logs and stones. It is the nature of logs and stones to remain still on level ground and move on steep ground; if square, they stop, and if round, they roll. Therefore, the strategic force of one skilled at directing men in battle is like rolling round stones down a mountain a thousand fathoms high. This is strategic force.

Sunzi said: In general, the one who occupies the battlefield first and waits for the enemy is rested; the one who arrives later and rushes into battle is weary. Therefore, one skilled in warfare makes the enemy come to him and is not made to go to the enemy.

What makes the enemy come of his own accord is the prospect of profit; what keeps the enemy from coming is the prospect of harm. Therefore, if the enemy is rested, you can wear him down; if he is well fed, you can starve him; if he is settled, you can make him move. Emerge where he must hurry to defend; hurry to where he does not expect you.

An army can march a thousand miles without weariness when it travels through ground where there is no enemy. An attack is certain to succeed when it strikes where the enemy does not defend. A defense is certain to hold when it guards what the enemy does not attack. Therefore, against one skilled in attack, the enemy does not know where to defend; against one skilled in defense, the enemy does not know where to attack. Subtle, so subtle that he reaches the formless; mysterious, so mysterious that he makes no sound. Thus, he can become the arbiter of the enemy’s fate.

An advance that cannot be resisted strikes the enemy’s empty places. A retreat that cannot be pursued moves so swiftly that it cannot be overtaken. Therefore, if I want battle, even though the enemy has high ramparts and deep ditches, he will have no choice but to fight me because I attack a place he must rescue. If I do not want battle, even if I defend only a line drawn on the ground, the enemy will be unable to fight me because I divert him from the direction he wants to take.

Therefore, expose the enemy’s disposition while remaining formless yourself, and your forces will be concentrated while the enemy’s are divided. If we are concentrated into one force while the enemy is divided into ten, then we use ten against one. Thus, we are many and the enemy is few. If we can use many to strike few, then those we actually fight will be limited. The enemy must not know the ground on which we intend to fight. If he does not know it, he must prepare in many places. If he prepares in many places, those we actually fight in any one place will be few. If he prepares the front, his rear will be weak; if he prepares the rear, his front will be weak; if he prepares the left, his right will be weak; if he prepares the right, his left will be weak. If he prepares everywhere, he will be weak everywhere. The side with few troops is the one that prepares against others; the side with many is the one that makes others prepare against it.

Therefore, if you know the place and day of battle, you can march a thousand miles and assemble to fight. If you know neither the place nor the day of battle, the left cannot rescue the right, the right cannot rescue the left, the front cannot rescue the rear, and the rear cannot rescue the front. How much more is this true when distant units are tens of miles apart and even nearby units are several miles apart? By my assessment, even though the troops of Yue are numerous, how can that help them determine victory or defeat? Thus it is said: Victory can be taken into one’s own hands. Even if the enemy is numerous, he can be prevented from fighting effectively.

Therefore, calculate the enemy’s plans and learn their strengths and weaknesses. Provoke him and learn the principles governing his movement and stillness. Expose his disposition and learn the ground of death and life. Probe him and learn where he has more than enough and where he has too little. Therefore, the ultimate disposition of an army is to reach formlessness. When it is formless, even deeply placed spies cannot observe it, and wise advisers cannot devise plans against it. In response to the enemy’s disposition, lay victory before the multitude, but the multitude cannot understand it. Everyone knows the disposition by which I won, but no one knows the disposition by which I controlled the victory. Therefore, a victorious method is not repeated but adapts its disposition in endlessly varying ways.

The disposition of an army resembles water. Water’s movement avoids high ground and rushes downward; an army’s victory avoids solidity and strikes emptiness. Water determines its course according to the ground; an army determines victory according to the enemy. Therefore, an army has no fixed strategic force and no constant disposition. One who can change and transform according to the enemy and thereby win is called divine. Of the Five Phases, none is constantly dominant. Of the four seasons, none remains in place. The days are short and long; the moon wanes and waxes.

Sunzi said: As a general rule for employing an army, the commander receives his orders from the ruler, assembles the army and gathers the troops, and establishes camp when the forces confront each other. Nothing is more difficult than the contest for advantage. The difficulty in the contest for advantage is turning the indirect into the direct and misfortune into advantage. Therefore, take an indirect route, lure the enemy with profit, set out after him, and arrive before him. This is understanding the calculation of indirect and direct routes.

Thus, the contest for advantage can bring profit, and the contest for advantage can bring danger. If the entire army competes for advantage, it will not arrive in time. If the army is abandoned to compete for advantage, the baggage and heavy equipment will be lost. Therefore, if troops roll up their armor and rush forward, stopping neither day nor night and doubling their normal marches, then in a contest for advantage a hundred miles away, the commanders of all three armies will be captured. The strong arrive first, the weary fall behind, and by this method only one-tenth arrive. In a contest for advantage fifty miles away, the commander of the vanguard will be defeated, and by this method only half arrive. In a contest for advantage thirty miles away, two-thirds arrive. Thus, an army without baggage and heavy equipment is lost; without provisions it is lost; without stored supplies it is lost. Therefore, one who does not know the plans of the other lords cannot form alliances in advance. One who does not know the terrain of mountains, forests, dangerous defiles, obstacles, and marshes cannot march an army. One who does not employ local guides cannot obtain the advantages of the ground.

Therefore, an army is established through deception, moves for advantage, and changes through division and concentration. Thus, let its speed be like the wind, its measured movement like a forest, its invasion and plundering like fire, and its immovability like a mountain. Let it be as difficult to know as darkness and move like a thunderclap. When plundering the countryside, divide your forces; when expanding your territory, divide the gains. Weigh the balance and then move. The one who first understands the calculation of indirect and direct routes will win. This is the method of the contest for advantage.

The Military Administration says: “Because spoken words cannot be heard from one unit to another, gongs and drums are used. Because soldiers cannot see one another, banners and flags are used.” Gongs, drums, banners, and flags unify the people’s ears and eyes. Once the people are unified, the brave cannot advance alone and the cowardly cannot retreat alone. This is the method of employing large forces. Therefore, in night battles use many gongs and drums, and in daytime battles use many banners and flags. These redirect the soldiers’ ears and eyes according to circumstances.

The spirit of an entire army can be taken away, and a commander’s resolve can be taken away. Thus, in the morning, spirit is keen; during the day, it becomes sluggish; by evening, it turns toward home. Therefore, one skilled in employing an army avoids the enemy when his spirit is keen and strikes him when his spirit is sluggish and turning homeward. This is controlling spirit. Waiting in good order for disorder and in calm for clamor is controlling the mind. Waiting near the battlefield for an enemy coming from far away, waiting rested for the weary, and waiting well fed for the hungry is controlling strength. Do not intercept banners in perfect order, and do not attack an imposing formation. This is controlling change.

Therefore, the method of employing an army is this: do not advance uphill against an enemy on high ground; do not oppose an enemy with hills behind him; do not pursue an enemy who feigns retreat; do not attack elite troops whose ardor is keen; do not swallow bait offered by enemy troops; do not block an army returning home; when surrounding an army, always leave an opening; do not press a desperate enemy. This is the method of employing an army.

Sunzi said: As a general rule for employing an army, the commander receives his orders from the ruler, assembles the army, and gathers the troops. Do not camp on difficult ground. Join alliances on crossroads ground. Do not linger on isolated ground. Make plans on encircled ground. Fight on death ground. There are roads that must not be taken, armies that must not be attacked, cities that must not be assaulted, ground that must not be contested, and commands from the ruler that must not be obeyed. Therefore, a commander who understands the advantages of the nine variations knows how to employ an army. A commander who does not understand the advantages of the nine variations may know the terrain but cannot obtain its advantages. One who directs an army without knowing the methods of the nine variations may know the advantages of the ground but cannot make full use of his men.

Therefore, the wise person’s deliberations always combine advantage and harm. By considering harm within advantage, his undertaking can be trusted to succeed; by considering advantage within harm, his troubles can be resolved. Therefore, subdue the other lords by threatening harm, keep them occupied with burdensome affairs, and make them hurry after profit.

Therefore, the method of employing an army is not to rely on the enemy’s not coming, but to rely on having the means to await him; not to rely on his not attacking, but to rely on having a position he cannot attack.

Therefore, a commander faces five dangers: if determined to die, he can be killed; if determined to survive, he can be captured; if quick-tempered, he can be provoked; if scrupulously honorable, he can be humiliated; if he loves the people, he can be harassed. These five are faults in a commander and disasters in employing an army. The destruction of an army and the death of its commander will certainly result from these five dangers, so they must be carefully examined.

Sunzi said: In general, when positioning an army and observing the enemy, cross mountains by keeping near valleys. Occupy high ground facing the sunny side. When fighting on elevated ground, do not climb up to engage the enemy. This is how to position an army in mountains. After crossing a river, move far away from it. When an invading enemy is crossing a river, do not meet him in the water. Let half his force cross and then attack it; this is advantageous. If you want battle, do not face the invader close to the riverbank. Occupy high ground facing the sunny side, and do not face the current. This is how to position an army near water. When crossing salt marshes, leave quickly and do not linger. If you encounter an enemy within a salt marsh, stay close to water and grass, with many trees behind you. This is how to position an army in salt marshes. On level ground, occupy open terrain with high ground to your right and rear, death ground in front, and life ground behind. This is how to position an army on level ground. The advantages of these four ways of positioning an army enabled the Yellow Emperor to defeat the four emperors.

Every army prefers high ground and dislikes low ground, values the sunny side and avoids the shady side, stays where life can be sustained, and occupies solid ground. Then the army will be free of the many illnesses, and this means certain victory. On hills, embankments, and dikes, always occupy the sunny side and keep them to your right and rear. These are military advantages and assistance from the ground. When rain falls upstream and foam comes down the river, those wishing to cross should wait until the water has settled.

Whenever the ground contains impassable ravines, natural wells, natural prisons, natural nets, natural pits, or natural fissures, leave them quickly and do not approach them. Keep them far from us and near the enemy; face them while making the enemy put his back to them. If near the army there are dangerous defiles, ponds, reed beds, forests, or dense thickets, they must be searched carefully and repeatedly. These are places where ambushes and spies hide.

An enemy who is near and remains quiet relies on the difficulty of his position. One who is far away and challenges you to battle wants you to advance. If the ground he occupies is easy, it offers him an advantage. Movement among many trees means the enemy is approaching. Many screens set up in the grass create suspicion. Birds taking flight indicate an ambush. Startled animals indicate a surprise attack. Dust rising high and sharp indicates chariots approaching. Dust that stays low and spreads broadly indicates infantry approaching. Dust dispersed in separate strands indicates parties gathering firewood. Small clouds of dust moving back and forth indicate an army making camp. Humble words accompanied by increased preparations indicate an advance. Forceful words accompanied by an aggressive forward drive indicate a retreat. Light chariots emerging first and taking positions on the flanks indicate formation for battle. A request for peace without a prior agreement indicates a plot. Troops running about and taking up formation indicate that the appointed time for battle has come. Half advancing and half retreating indicates a lure. Soldiers standing while leaning on their weapons are hungry. Men drawing water and drinking before carrying it back are thirsty. Seeing an advantage but not advancing indicates weariness. Birds gathering over a place indicate that it is empty. Cries in the night indicate fear. Disorder in the army indicates that the commander lacks authority. Moving banners and flags indicate confusion. Angry officers indicate exhaustion. Feeding grain to horses, slaughtering pack animals for food, putting away cooking pots, and not returning to shelters indicate a desperate enemy. Men whispering together in small groups and speaking softly indicate that the commander has lost the troops. Frequent rewards indicate distress. Frequent punishments indicate severe difficulty. A commander who begins with brutality and later fears his troops is extremely incompetent. An enemy who sends envoys with conciliatory words wants a respite. When opposing troops angrily confront each other but neither engage nor withdraw for a long time, the situation must be carefully examined.

Therefore, an army does not benefit merely from having more troops. It is enough not to advance recklessly, to concentrate strength, assess the enemy, and win the loyalty of the troops. One who is thoughtless and underestimates the enemy will certainly be captured.

If soldiers are punished before they have become attached to their commander, they will not submit. If they do not submit, they will be difficult to employ. If soldiers have already become attached but punishments are not enforced, they cannot be employed. Therefore, command them through civil methods and bring them into line through martial discipline. This means certain success. If orders are consistently enforced when the people are trained, the people will submit. If orders are not consistently enforced when the people are trained, the people will not submit. Consistent enforcement of orders means that the commander and the troops are in harmony.

Sunzi said: In general, terrain may be accessible, entangling, temporizing, constricted, precipitous, or distant. Ground over which we can go and the enemy can come is called accessible. On accessible terrain, first occupy high ground on the sunny side and keep your supply routes open; then it is advantageous to fight. Ground over which one can go but from which it is difficult to return is called entangling. On entangling terrain, if the enemy is unprepared, go out and defeat him. If the enemy is prepared and you go out but do not defeat him, it will be difficult to return, and this is disadvantageous. Ground on which it is disadvantageous for us to go out and disadvantageous for the enemy to come out is called temporizing. On temporizing terrain, even if the enemy offers us an advantage, we should not go out. Draw back and leave; when half the enemy’s army has emerged, attack it, and this will be advantageous. On constricted terrain, if we occupy it first, we must fill it with troops and await the enemy. If the enemy occupies it first and has filled it with troops, do not follow him in; if he has not filled it, follow him in. On precipitous terrain, if we occupy it first, we must hold high ground on the sunny side and await the enemy. If the enemy occupies it first, draw back and leave; do not follow him. On distant terrain, when strategic conditions are equal, it is difficult to provoke battle, and fighting brings no advantage. These six are the principles of terrain. Examining them is the commander’s highest responsibility and cannot be neglected.

Thus, an army may flee, become insubordinate, collapse, crumble, fall into disorder, or be routed. These six are not disasters from Heaven but faults of the commander. When strategic conditions are equal and one is sent against ten, the result is flight. When the soldiers are strong and the officers weak, the result is insubordination. When the officers are strong and the soldiers weak, the result is collapse. When senior officers are angry and disobedient, encounter the enemy, and resentfully fight on their own because the commander does not understand their capabilities, the result is crumbling. When the commander is weak and not strict, his instructions are unclear, officers and soldiers have no fixed duties, and formations are deployed haphazardly, the result is disorder. When the commander cannot assess the enemy, pits a small force against a large one, attacks strength with weakness, and has no selected vanguard, the result is rout. These six are ways to defeat. Examining them is the commander’s highest responsibility and cannot be neglected.

Terrain is an army’s aid. Assessing the enemy to control victory and calculating dangers, narrow passes, and distances are the way of a superior commander. One who knows these things and uses them in battle will certainly win; one who does not know them and uses battle will certainly lose. Therefore, if the principles of battle indicate certain victory, it is permissible to fight even if the ruler says not to fight. If the principles of battle indicate that victory is impossible, it is permissible not to fight even if the ruler says to fight. Thus, a commander who advances without seeking fame and retreats without avoiding blame, whose only concern is protecting the people and whose actions accord with the ruler’s interests, is the treasure of the state.

Regard your soldiers as infants, and you can lead them into the deepest ravines. Regard your soldiers as beloved sons, and you can die together with them. But if you treat them generously and cannot employ them, love them and cannot command them, or let them become disorderly and cannot govern them, they are like spoiled children and cannot be used.

Knowing that our soldiers can attack but not knowing that the enemy cannot be attacked gives only half the assurance of victory. Knowing that the enemy can be attacked but not knowing that our soldiers cannot attack gives only half the assurance of victory. Knowing that the enemy can be attacked and that our soldiers can attack, but not knowing that the terrain does not permit battle, gives only half the assurance of victory. Therefore, one who understands warfare moves without confusion and acts without exhausting his resources. Thus it is said: Know the enemy and know yourself, and your victory will not be imperiled. Know Heaven and know Earth, and your victory can be complete.

Sunzi said: As a general rule for employing an army, there is dispersive ground, light ground, contested ground, intersecting ground, crossroads ground, heavy ground, difficult ground, encircled ground, and death ground. When the other lords fight within their own territory, it is dispersive ground. When one enters another’s territory but not deeply, it is light ground. Ground advantageous to us if we gain it and advantageous to the enemy if he gains it is contested ground. Ground over which we can go and the enemy can come is intersecting ground. Territory adjoining three other states, where the first to arrive can gain the support of the multitudes under Heaven, is crossroads ground. When one has penetrated deeply into another’s territory and has passed many walled cities and towns, it is heavy ground. Mountains, forests, dangerous defiles, obstacles, marshes, and every route that is difficult to travel are difficult ground. Ground whose entrance is narrow, whose route of return is circuitous, and where a small enemy force can strike our large force is encircled ground. Ground where fighting quickly brings survival and failure to fight quickly brings destruction is death ground. Therefore, do not fight on dispersive ground; do not stop on light ground; do not attack on contested ground; do not let your forces become cut off on intersecting ground; join alliances on crossroads ground; plunder supplies on heavy ground; keep moving on difficult ground; make plans on encircled ground; and fight on death ground.

Those who in ancient times were said to be skilled in employing an army could keep the enemy’s front and rear from reaching each other, his large and small forces from relying on each other, his high-ranking and low-ranking men from rescuing each other, and his superiors and subordinates from supporting each other. They could keep separated soldiers from assembling and assembled troops from becoming orderly. They moved when it accorded with advantage and stopped when it did not accord with advantage. Someone may dare to ask: “If the enemy is numerous, orderly, and about to advance, how should we meet him?” I reply: “First seize something he cherishes, and he will obey you.” The essential nature of warfare is speed: exploit the enemy’s failure to reach a position, travel by routes he does not anticipate, and attack where he is not on guard.

In general, the way of an invading army is that when it penetrates deeply, its troops become united and the defenders cannot overcome it. Plunder fertile country so that the entire army has sufficient food. Carefully nurture the troops and do not weary them. Unite their spirit and accumulate their strength. Maneuver the army and devise plans so that your intentions cannot be fathomed. Throw the troops into a place from which there is nowhere to go, and they will die rather than flee. If they are ready to die, how can officers and soldiers fail to exert their full strength? When soldiers are in extreme danger, they do not fear. When there is nowhere to go, they stand firm. When they penetrate deeply, they hold together. When they have no alternative, they fight. Therefore, such troops stay alert without being drilled, do what is wanted without being asked, are close-knit without agreements, and can be trusted without commands. Prohibit omens and eliminate doubts, and they will go nowhere else even until death. If my officers have no surplus wealth, it is not because they despise material goods. If they have no expectation of surviving, it is not because they dislike long life. On the day the order to advance is issued, seated officers and soldiers wet their lapels with tears, while those lying down let tears run across their cheeks. But throw them into a place from which there is nowhere to go, and they will show the courage of Zhuan Zhu and Cao Gui.

Therefore, one skilled in employing an army is like the Swiftly Striking snake. The Swiftly Striking snake lives on Mount Chang. Strike its head, and its tail arrives; strike its tail, and its head arrives; strike its middle, and both head and tail arrive. Someone may dare to ask: “Can an army be made to act like the Swiftly Striking snake?” I reply: “It can. The people of Wu and the people of Yue hate each other, but if they are crossing a river in the same boat and encounter a storm, they rescue each other like the left and right hands.” Therefore, tethering horses and burying chariot wheels are not enough to rely on. Making everyone equally courageous is the way of government. Making full use of both the strong and the weak is the principle of terrain. Therefore, one skilled in employing an army leads his troops hand in hand as if they were one person, because they have no alternative.

The business of a commander is to remain calm and inscrutable, upright and disciplined. He must be able to keep the eyes and ears of his officers and soldiers ignorant, so that they know nothing. He changes his undertakings and alters his plans, so that others cannot recognize them. He changes his encampments and takes circuitous routes, so that others cannot anticipate him. When a commander gives his troops their appointed task, it is like climbing to a height and then removing the ladder. When a commander leads them deeply into the territory of another lord and releases the trigger, he burns the boats and smashes the cooking pots. He drives them like a flock of sheep, driving them there and driving them back, with none knowing where they are going. Gathering the army’s multitudes and throwing them into danger is called the business of a commander. The variations of the nine kinds of ground, the advantages of contraction and extension, and the principles of human nature must be carefully examined.

In general, the way of an invading army is that deep penetration brings unity, while shallow penetration brings dispersion. When an army has left its own state and crossed the border, it is on isolated ground. Ground open in all four directions is crossroads ground. Deep penetration is heavy ground. Shallow penetration is light ground. Ground with strong positions behind and narrow passages ahead is encircled ground. Ground from which there is nowhere to go is death ground. Therefore, on dispersive ground, I will unify the troops’ purpose. On light ground, I will keep the units connected. On contested ground, I will hurry up the rear. On intersecting ground, I will carefully guard the defenses. On crossroads ground, I will strengthen alliances. On heavy ground, I will maintain a continuous supply of food. On difficult ground, I will press forward along the route. On encircled ground, I will block the openings. On death ground, I will show the troops that they cannot survive. The nature of soldiers is to resist when surrounded, fight when they have no alternative, and obey when in extreme danger.

Therefore, one who does not know the plans of the other lords cannot form alliances in advance. One who does not know the terrain of mountains, forests, dangerous defiles, obstacles, and marshes cannot march an army. One who does not employ local guides cannot obtain the advantages of the ground. One who does not know even one of these four or five matters does not command the army of a hegemonic king. When the army of a hegemonic king attacks a great state, that state’s masses cannot assemble. When his power bears down on the enemy, the enemy’s allies cannot unite. Therefore, he does not contend for alliances with all under Heaven and does not foster the power of all under Heaven. He trusts his own private designs and brings his power to bear upon the enemy. Thus, the enemy’s cities can be taken and his state can be brought down. Bestow rewards that go beyond established rules and issue commands that go beyond ordinary government. Direct the army’s multitudes as though employing one person. Set them to tasks, but do not explain your words; lead them toward advantage, but do not tell them of the harm. Throw them onto ground of destruction, and only then will they survive; sink them into death ground, and only then will they live. Only after the troops have fallen into danger can they determine victory or defeat. Therefore, the business of warfare lies in pretending to comply with the enemy’s intentions, concentrating against him in a single direction, and killing his commander a thousand miles away. This is called accomplishing a task through skill and ability.

Therefore, on the day the government mobilizes the army, close the border passes and break the tallies, allowing none of the enemy’s envoys to pass. Debate the undertaking rigorously in the ancestral temple to decide its course. When the enemy opens and closes an opportunity, you must rush in. Seize first what he cherishes, while concealing the time appointed for battle. Follow established measures while adapting to the enemy, and thereby decide the battle. Thus, at first be like a secluded maiden, and the enemy will open his door. Afterward be like an escaping hare, and the enemy will be unable to resist in time.

Sunzi said: There are five kinds of attack by fire. The first is burning enemy soldiers; the second is burning accumulated supplies; the third is burning baggage trains; the fourth is burning arsenals and storehouses; and the fifth is burning transport routes. To carry out a fire attack, there must be a means of starting it, and incendiary materials must always be prepared. There are suitable times for setting fires and suitable days for raising them. The suitable time is when the weather is dry. The suitable days are when the moon is in the constellations of the Winnowing Basket, Wall, Wings, or Chariot Platform. Whenever the moon is in these four constellations, it is a day when winds arise.

In every fire attack, you must respond according to the changes produced by the five kinds of fire. When fire breaks out inside the enemy’s camp, respond early with an attack from outside. If fire breaks out but the enemy’s troops remain calm, wait and do not attack. When the fire reaches its greatest strength, follow up if you can; if you cannot, stop. If fire can be set from outside, do not wait for an agent within; set it when the time is right. When a fire is set upwind, do not attack from downwind. A wind that lasts through the day will cease at night. Every army must understand the changes produced by the five kinds of fire and guard for the proper conditions. Thus, using fire to support an attack produces brilliant results; using water to support an attack produces strength. Water can cut an enemy off, but it cannot seize his resources.

To win battles and take objectives but fail to consolidate the achievement is disastrous. This is called “wasteful delay.” Therefore it is said: An enlightened ruler considers the matter carefully, and an excellent commander carries it through. Do not move unless there is advantage; do not employ troops unless there is something to gain; do not fight unless there is danger. A ruler must not mobilize an army out of anger, and a commander must not bring on a battle out of resentment. Move when it accords with advantage; stop when it does not accord with advantage. Anger can turn back into pleasure, and resentment can turn back into delight, but a destroyed state cannot be restored to existence, and the dead cannot be restored to life. Therefore, an enlightened ruler is cautious, and an excellent commander is vigilant. This is the way to keep the state secure and the army intact.

Sunzi said: In general, when an army of a hundred thousand is raised and sent on a campaign a thousand miles away, the people’s expenses and the state’s expenditures amount to a thousand pieces of gold a day. There is turmoil at home and abroad, people are exhausted on the roads, and seven hundred thousand households are unable to pursue their work. Armies may confront each other for several years to contend for victory on a single day. If, out of reluctance to spend rank, salary, and a hundred pieces of gold, one fails to learn the enemy’s situation, this is the height of inhumanity. Such a person is no commander of men, no assistant to a ruler, and no master of victory. What enables enlightened rulers and worthy commanders to move and defeat others, achieving successes beyond the multitude, is foreknowledge. Foreknowledge cannot be obtained from ghosts and spirits, cannot be inferred from analogous events, and cannot be verified by calculations. It must be obtained from people who know the enemy’s situation.

Therefore, there are five kinds of spies: local spies, inside spies, converted spies, doomed spies, and surviving spies. When all five kinds operate together and no one knows their methods, this is called the “divine web,” and it is a ruler’s treasure. Local spies are recruited from the enemy’s local people. Inside spies are recruited from the enemy’s officials. Converted spies are recruited from the enemy’s spies. Doomed spies are used when we spread deceptive information outside, let our own spies know it, and have them transmit it to the enemy’s spies. Surviving spies are those who return with reports.

Therefore, of all relationships in the army, none should be closer than that with spies; no rewards should be more generous than those given to spies; and no affairs should be more secret than espionage. Without sagacious wisdom, one cannot employ spies. Without benevolence and righteousness, one cannot use spies effectively. Without subtlety and ingenuity, one cannot obtain the truth from spies. Subtle, so subtle! There is nowhere spies are not employed. If an espionage operation has not yet been carried out but is heard of in advance, both the spy and the person he told must be put to death.

Whenever there is an army we wish to strike, a city we wish to attack, or a person we wish to kill, we must first learn the names of the defending commander, his attendants, those who announce visitors, the gatekeepers, and the members of his staff. Order our spies to seek out and learn all of them. We must seek out enemy spies who have come to spy on us, then bribe them, guide them, and lodge them well. In this way, converted spies can be obtained and employed. Through the information gained from them, local spies and inside spies can be found and employed. Through the information gained from them, deceptive operations can be devised so that doomed spies can transmit false information to the enemy. Through the information gained from them, surviving spies can be sent and made to return at the appointed time. The ruler must know the work of all five kinds of spies, and this knowledge must depend on converted spies. Therefore, converted spies must be treated with the greatest generosity.

In ancient times, when the Yin rose to power, Yi Zhi was in Xia. When the Zhou rose to power, Lü Ya was in Yin. Therefore, an enlightened ruler or worthy commander who can use people of the highest wisdom as spies will certainly accomplish great achievements. This is the essential element of warfare, on which the entire army relies in order to move.