The Art of War

So base it on five factors, compare the two sides by calculation, and search out their true conditions. The first is the Way, the second Heaven, the third terrain, the fourth the general, the fifth method.

The Way is what makes the people one in purpose with those above them, so that they will die with them and live with them and not fear danger. Heaven is yin and yang, cold and heat, the order of the seasons. Terrain is far and near, rugged and level, broad and narrow, deadly and life-giving. The general is wisdom, trustworthiness, humaneness, courage, and strictness. Method means regulations: the organization of units, the ranks of officers, and the management of supplies. Every general has heard of these five. Those who know them win; those who do not know them do not win.note

So compare the two sides by calculation and search out their true conditions. Ask: Which ruler has the Way? Which general has ability? Which side has Heaven and terrain in its favor? Whose regulations and orders are carried out? Whose troops are stronger? Whose officers and soldiers are better trained? Whose rewards and punishments are clearer? By these I know victory and defeat.

Now, the side that wins in the calculations in the temple before battle has many counts in its favor. The side that does not win in the calculations in the temple before battle has few. Many counts win; few counts do not win. How much less with no counts at all! By looking at this, I can see victory and defeat.note

Sunzi said: As a rule, in the method of using troops there are a thousand swift four-horse chariots, a thousand leather-covered wagons, and a hundred thousand armored soldiers, with grain carried a thousand li. There are expenses at home and in the field, the costs of envoys and guests, materials such as glue and lacquer, and the upkeep of chariots and armor. These cost a thousand pieces of gold a day. Only then can an army of a hundred thousand be raised.note

When troops are used in battle and victory is slow in coming, the troops are worn down and their edge is blunted. When they attack cities, their strength is exhausted. When the army is long exposed in the field, the state’s resources will not suffice.

When the troops are worn down and their edge blunted, their strength exhausted and their wealth spent, the other lords will exploit this weakness and rise up. Then even the wise cannot set the aftermath right. So in war we have heard of clumsy speed, but we have never seen cleverness that drags on. No state has ever gained from a drawn-out war.

So one who does not fully know the harm in using troops cannot fully know the benefit of using troops.

Those skilled at using troops do not levy conscripts twice or ship grain three times. They take their equipment from home and their grain from the enemy. So the army’s food can be sufficient.

A state is impoverished by its army through long-distance transport. Long-distance transport impoverishes the common people. Near the army, goods sell dear. When goods sell dear, the people’s wealth is drained. When wealth is drained, local levies grow pressing. With strength exhausted and wealth spent, the households of the heartland are emptied. Of the people’s means, seven parts in ten are gone. Of the public means, six parts in ten are gone: broken chariots and worn-out horses, armor and helmets, bows and arrows, halberds and shields, spears and large shields, draft oxen and heavy wagons.

So a wise general strives to feed off the enemy. One zhong of the enemy’s food is worth twenty zhong of our own. One shi of the enemy’s fodder is worth twenty shi of our own.note

So killing the enemy comes from anger. Taking the enemy’s spoils comes from reward. In chariot fighting, when ten or more chariots are captured, reward those who captured the first, and change the chariots’ flags and banners. Mix the captured chariots in with ours and ride them. Treat the captured soldiers well and care for them. This is called defeating the enemy and growing stronger.

So in war, value victory, not duration. So the general who knows war decides the fate of the people and is the master of the state’s safety or danger.

So those skilled at using troops subdue the enemy’s army, but not by fighting. They take the enemy’s cities, but not by attacking. They destroy the enemy’s state, but not by a long war. They must contend for all under Heaven by keeping things whole. So the troops are not worn down and the advantage can be kept whole. This is the method of planning the attack.

So in the method of using troops: with ten times their number, surround them. With five times, attack them. With double, divide them. When evenly matched, be able to fight them. When fewer, be able to defend against them. When not their equal, be able to avoid them. So a small force that holds out stubbornly is captured by a large one.

The general is the state’s support. If the support fits closely, the state will surely be strong. If the support has gaps, the state will surely be weak.

So there are three ways the army suffers at the hands of the ruler. Not knowing that the army cannot advance and ordering it to advance; not knowing that the army cannot retreat and ordering it to retreat: this is called tethering the army. Not knowing the affairs of the army yet sharing in its administration: then the soldiers are confused. Not knowing the army’s need for flexible command yet sharing in its appointments: then the soldiers are suspicious. Once the army is both confused and suspicious, trouble from the other lords arrives. This is called disordering the army and handing the enemy victory.note

So there are five ways to know victory. Those who know when they can fight and when they cannot will win. Those who understand how to use large and small forces will win. Those whose high and low share the same desire will win. Those who are prepared and wait for the unprepared will win. Those whose general is able and whose ruler does not hold the reins will win. These five are the way to know victory.

Sunzi said: Those skilled in war in ancient times first made themselves unbeatable, then waited for the enemy to become beatable. Being unbeatable lies with oneself. Being beatable lies with the enemy. So those skilled in war can make themselves unbeatable, but cannot make the enemy surely beatable. So it is said: Victory can be known, but it cannot be made.

Being unbeatable is a matter of defense. Being beatable is a matter of attack. Defend when strength is lacking; attack when it is abundant. Those skilled in defense hide beneath the ninefold earth. Those skilled in attack move above the ninefold heavens. So they can protect themselves and win complete victory.

To see a victory that is no more than what the crowd can see is not the best of the best. To win in battle and have all under Heaven say “Well done” is not the best of the best. So lifting a strand of autumn down takes no great strength. Seeing the sun and moon takes no sharp eyes. Hearing thunder takes no keen ears.

In the method of warfare there are: first, measurement; second, quantity; third, count; fourth, weighing; fifth, victory. Terrain gives rise to measurement. Measurement gives rise to quantity. Quantity gives rise to count. Count gives rise to weighing. Weighing gives rise to victory. So the victorious army is like a yi weighed against a zhu. The defeated army is like a zhu weighed against a yi. The victor’s fighting is like water stored behind a dam and cut loose into a gorge a thousand ren deep. This is disposition.note

Sunzi said: As a rule, governing many is like governing few: it is a matter of organization. Fighting with many is like fighting with few: it is a matter of signals. That the whole army can meet the enemy and never be defeated is a matter of the unorthodox and the orthodox. That troops strike like a whetstone thrown at an egg is a matter of empty and full.note

The swiftness of rushing water, to the point of sweeping boulders away: this is strategic power. The swiftness of a bird of prey, to the point of smashing and breaking its quarry: this is timing. So for those skilled in war, their strategic power is steep and their timing is short. Strategic power is like a crossbow fully drawn. Timing is like the trigger let go.note

In the tangle and swirl, they fight amid disorder yet cannot be thrown into disorder. In the churning and murk, their formation is round yet they cannot be defeated. Disorder arises from order. Cowardice arises from courage. Weakness arises from strength. Order and disorder are a matter of organization. Courage and cowardice are a matter of strategic power. Strength and weakness are a matter of disposition.

So those skilled at moving the enemy show them a form, and the enemy will follow it. They offer them something, and the enemy will take it. Move them with advantage; await them with the main force.

So those skilled in war seek it in strategic power and do not demand it of individuals. So they can choose their people and rely on strategic power. Those who rely on strategic power send people into battle the way one rolls logs and stones. It is the nature of logs and stones to be still when stable and to move when on a slope, to stop when square and to roll when round. So the strategic power of those skilled at sending people into battle is like rolling round boulders down a mountain a thousand ren high. This is strategic power.

Sunzi said: As a rule, whoever occupies the battleground first and awaits the enemy is rested. Whoever occupies the battleground later and hurries into battle is weary. So those skilled in war make others come to them and are not made to come to others.

To be able to make the enemy come on their own is to offer them advantage. To be able to keep the enemy from coming is to threaten them with harm. So when the enemy is rested, be able to tire them. When they are well fed, be able to starve them. When they are settled, be able to move them.

Go out where they do not hurry; hurry where they do not expect.

To march a thousand li without weariness is to march through land where there is no one. To attack and surely take is to attack where they do not defend. To defend and surely hold is to defend where they do not attack. So against those skilled in attack, the enemy does not know where to defend. Against those skilled in defense, the enemy does not know where to attack. Subtle, so subtle—to the point of formlessness! Divine, so divine—to the point of soundlessness! So they can decide the enemy’s fate.

To advance where none can stop us is to strike at their empty points. To withdraw and not be pursued is to be too swift to be overtaken. So if we want battle, the enemy cannot help but fight us, even behind high ramparts and deep moats, because we attack what they must rescue. If we do not want battle, the enemy cannot fight us, even if we only draw a line on the ground and hold it, because we divert them from where they are going.note

So if we make others show their form while we have none, then we are concentrated and the enemy is divided. We are concentrated into one; the enemy is divided into ten. This is using ten to attack their one. Then we are many and the enemy few. If we can strike the few with the many, then those we fight will be limited. The ground where we will fight cannot be known. If it cannot be known, the enemy prepares in many places. If the enemy prepares in many places, those we fight will be few. So if they prepare the front, they are few at the rear. If they prepare the rear, they are few at the front. If they prepare the left, they are few on the right. If they prepare the right, they are few on the left. If there is nowhere they do not prepare, there is nowhere they are not few. To be few is to prepare against others. To be many is to make others prepare against us.

So if we know the ground of battle and know the day of battle, we can march a thousand li and join battle. If we do not know the ground of battle and do not know the day of battle, then 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 less when the farthest are tens of li away and the nearest several li! Judging by Wu, though the troops of Yue are many, what good is that to their victory? So it is said: Victory can be made. Though the enemy is many, they can be kept from fighting.note

So: assess them, and learn the calculation of gain and loss; provoke them, and learn the pattern of their movement and stillness; make them show their form, and learn the ground of death and life; probe them, and learn where they have more than enough and where not enough.

So the ultimate in giving troops a form is to reach formlessness. If we are formless, the deepest spies cannot peer in, and the wise cannot lay plans against us. Following the form of things, we set victory before the crowd, and the crowd cannot understand it. Everyone knows the form by which we won, but no one knows the form by which we shaped the victory. So victories in battle are not repeated; they answer to form without end.

So of the five phases, none always prevails; of the four seasons, none keeps a constant place; the days are short and long; the moon dies and comes to life.note

Sunzi said: As a rule, in the method of using troops, the general takes orders from the ruler, assembles the army, gathers the troops, and makes camp facing the enemy. Nothing is harder than the contest for advantage. What is hard in the contest for advantage is to make the roundabout direct and to make adversity an advantage. So make your route roundabout and lure them with advantage; set out after others, arrive before others. This is knowing the calculation of the roundabout and the direct.

So the contest of an army brings advantage; the contest of a crowd brings danger. If you move the whole army to contest for advantage, you will not arrive in time; if you leave part of the army behind to contest for advantage, the baggage trains will be lost. For this reason, if you roll up your armor and hurry, not stopping day or night, marching double distance at double pace, and contest for advantage a hundred li away, the generals of all three armies will be captured: the vigorous go first, the exhausted lag behind, and as a rule one in ten will arrive. At fifty li, the general of the forward army will fall, and as a rule half will arrive. At thirty li, two-thirds will arrive. For this reason an army without baggage trains perishes; without grain and food it perishes; without stores it perishes.note

So one who does not know the plans of the other lords cannot form alliances in advance; one who does not know the form of mountains and forests, precipices and defiles, marshes and wetlands cannot march an army; one who does not use local guides cannot gain the advantages of the ground.

The Military Administration says: “Because spoken words cannot be heard, gongs and drums were made; because sight cannot reach, banners and flags were made.” Gongs and drums, banners and flags are the means of unifying people’s ears and eyes. Once people are united as one, the brave cannot go forward on their own, nor the timid fall back on their own. This is the method of using large numbers. So in night battles, use many fires and drums; in day battles, use many banners and flags. These are the means of changing what people hear and see.note

The spirit of the whole army can be taken from it; the heart of the general can be taken too. For this reason, spirit is sharp in the morning, slack by midday, and bent on home by evening. Those skilled at using troops avoid the enemy’s sharp spirit and strike when it is slack and bent on home: this is managing spirit. With order, await disorder; with calm, await clamor: this is managing the heart. From nearby, await those from afar; at ease, await the weary; well fed, await the hungry: this is managing strength. Do not intercept banners in tight, orderly ranks; do not attack formations drawn up in imposing array: this is managing change.

So in the method of using troops: do not go up against an enemy on high hills; do not meet head-on an enemy with a hill at its back; do not follow a feigned retreat; do not attack crack troops; do not take the bait of decoy troops; do not block an army returning home; to an encircled army you must leave an opening; do not pursue a desperate enemy. This is the method of using troops.

Sunzi said: As a rule, in the method of using troops, the general takes orders from the ruler, assembles the army, and gathers the troops. On broken ground, do not camp; on crossroads ground, join with allies; on cut-off ground, do not linger; on enclosed ground, make plans; on deadly ground, fight. There are roads one does not take, armies one does not strike, cities one does not attack, ground one does not contest, and commands of the ruler one does not accept. So a general who has mastered the advantages of the nine variations knows how to use troops. A general who has not mastered the advantages of the nine variations, even knowing the form of the terrain, cannot gain the advantages of the ground. One who directs troops without mastering the techniques of the nine variations, even knowing the five advantages, cannot get the full use of people.note

For this reason the deliberations of the wise always mix advantage and harm. When advantage is mixed in, the task can be relied on; when harm is mixed in, trouble can be dispelled. For this reason, bend the other lords with harm; keep them busy with tasks; set them rushing with advantage.

So in the method of using troops: do not rely on their not coming, but on our having the means to await them; do not rely on their not attacking, but on our being impossible to attack.

So a general has five dangers. Set on dying: can be killed. Set on living: can be captured. Quick to anger: can be taunted. Scrupulous about purity: can be disgraced. Loving the people: can be worn down. These five are faults in a general and disasters in using troops. When the army is wiped out and the general killed, the cause is always the five dangers. They must be examined with care.

Sunzi said: As a rule, in positioning the army and observing the enemy: cross mountains keeping close to valleys; face the side of life and occupy high ground; when the fighting is on the heights, do not climb up to it. This is positioning an army in the mountains. Having crossed water, be sure to move well away from it. When an invader crosses water to come at you, do not meet them in the water; strike when half have crossed: that is advantageous. If you want to fight, do not meet the invader close by the water; face the side of life and occupy high ground; do not face into the current. This is positioning an army near water. When crossing salt marshes, simply leave quickly and do not linger. If you meet the enemy in the middle of salt marshes, you must stay by water and grass and keep woods at your back. This is positioning an army in salt marshes. On level plains, occupy easy ground, with high ground on your right and at your back, death in front and life behind. This is positioning an army on level plains. The advantages of these four ways of positioning an army are how the Yellow Emperor defeated the four emperors.note

As a rule, an army likes the high and dislikes the low, values the sunny side and scorns the shady side. Nurture life, occupy solid ground, and the army will be free of the hundred illnesses: this is called certain victory. On hills, mounds, dikes, and embankments, you must occupy the sunny side, keeping them on your right and at your back. This is an advantage to the troops and help from the ground. When it has rained upstream and foam comes down, those who want to ford should wait until it settles.

As a rule, where the ground has steep gorges with torrents, Heaven’s Wells, Heaven’s Prisons, Heaven’s Nets, Heaven’s Pits, and Heaven’s Cracks, you must leave quickly and not go near. We keep far from them, and let the enemy be near them; we face them, and let the enemy have them at its back. When beside the army there are precipices and defiles, ponds and hollows, woods and trees, or reeds and rushes with dense cover, you must search them carefully and repeatedly: these are places where ambushers and spies hide.note

Near yet quiet: they are relying on their strong position. Far off yet provoking battle: they want the other side to advance. Camped on easy ground: it is to their advantage. Many trees moving: they are coming. Many screens in the grass: they mean to mislead. Birds rising: an ambush. Animals startled: a surprise attack. Dust high and sharp: chariots are coming. Low and broad: infantry is coming. Scattered and in streaks: they are gathering firewood. Sparse and moving to and fro: they are making camp. Humble words but increased preparations: they will advance. Strong words and driving forward: they will retreat. Light chariots coming out first and taking position on the flanks: they are forming up. Asking for peace without any agreement: a plot. Running about and setting out troops: the appointed time has come. Half advancing, half retreating: a lure. Leaning on their weapons as they stand: they are hungry. Drawing water and drinking first: they are thirsty. Seeing advantage but not advancing: they are exhausted. Birds gathering: the camp is empty. Shouting at night: they are afraid. The army in turmoil: the general lacks gravity. Banners and flags shifting: disorder. Officers angry: they are weary. Killing horses to eat the meat: the army has no grain. Hanging up their pots and not returning to their quarters: a desperate enemy. Murmuring and whispering, speaking to people slowly: the general has lost the troops. Frequent rewards: they are in straits. Frequent punishments: they are in distress. Harsh at first and then afraid of the troops: utterly inept. Envoys coming with gifts and apologies: they want a respite. When troops come at you in anger but for a long time neither engage nor withdraw, you must watch them with great care.

In war, more is not better. Only do not advance on force alone; it is enough to concentrate your strength, size up the enemy, and win people over. It is only the one who lacks forethought and takes the enemy lightly who will surely be captured by others.

If the soldiers are punished before they have bonded with you, they will not comply, and if they do not comply, they are hard to use. If they have bonded with you and punishments are not carried out, they cannot be used. So command them with civility and bring them into line with martial discipline: this is called certain success. If commands are consistently carried out in training the people, the people comply; if commands are not consistently carried out in training the people, the people do not comply. When commands are consistently carried out, leader and troops are in accord.

Sunzi said: Among the forms of terrain there are the accessible, the snaring, the stalemated, the narrow, the precipitous, and the distant. Where we can go and they can come: this is called accessible. On accessible terrain, be first to occupy the high and sunny side, and keep the supply routes secure; then fighting is advantageous. Where you can go but it is hard to return: this is called snaring. On snaring terrain, if the enemy is unprepared, go out and defeat them; if the enemy is prepared and you go out and do not win, it is hard to return: not advantageous. Where going out is not advantageous for us and going out is not advantageous for them: this is called stalemated. On stalemated terrain, even if the enemy offers us an advantage, we do not go out; we lead our troops away, and when half the enemy has come out, we strike: advantageous. On narrow terrain, if we occupy it first, we must man it fully and await the enemy. If the enemy occupies it first and has manned it fully, do not follow them in; if it is not fully manned, follow them in. On precipitous terrain, if we occupy it first, we must occupy the high and sunny side and await the enemy; if the enemy occupies it first, lead the troops away and do not follow them. On distant terrain, when strategic power is equal, it is hard to provoke battle, and fighting is not advantageous. These six are the way of the ground; they are the general’s utmost responsibility and must be examined with care.

So armies suffer flight, slackness, foundering, disintegration, disorder, and rout. These six are not disasters from Heaven and Earth but faults of the general. When strategic power is equal and one strikes ten: this is called flight. When the soldiers are strong and the officers weak: this is called slackness. When the officers are strong and the soldiers weak: this is called foundering. When the senior officers are angry and insubordinate, meet the enemy and fight on their own out of resentment, and the general does not know their abilities: this is called disintegration. When the general is weak and not strict, instruction and guidance are unclear, officers and soldiers have no constancy, and the troops are deployed every which way: this is called disorder. When the general cannot size up the enemy, engages many with few, strikes the strong with the weak, and the army has no picked vanguard: this is called rout. These six are the way of defeat; they are the general’s utmost responsibility and must be examined with care.

The form of the terrain is an aid to the army. To size up the enemy and shape victory, to calculate dangers and defiles, the distant and the near: this is the way of the superior general. One who knows this and fights will surely win; one who does not know this and fights will surely lose. So if the way of battle points to certain victory, even if the ruler says, “Do not fight,” it is right to fight. If the way of battle does not point to victory, even if the ruler says, “You must fight,” it is right not to fight. So a general who advances not to win a name and retreats not to escape punishment, who seeks only to protect the people and to serve the ruler’s interest, is the treasure of the state.

Look on your soldiers as babies, and they will go with you into deep ravines; look on them as your beloved children, and they will die at your side. Loving them but unable to command them, generous to them but unable to employ them, seeing their disorder but unable to bring them to order—they are like pampered children and cannot be used.

To know that our soldiers can strike, but not know that the enemy cannot be struck, is half of victory. To know that the enemy can be struck, but not know that our soldiers cannot strike, is half of victory. To know that the enemy can be struck and that our soldiers can strike, but not know that the form of the terrain does not allow battle, is half of victory. So those who know war move without confusion and act without coming to a dead end. So it is said: Know the other and know yourself, and victory will not be in danger; know Heaven and know the ground, and victory can be complete.

Sunzi said: In the method of using troops, there is scattering ground, there is light ground, there is contested ground, there is connecting ground, there is crossroads ground, there is heavy ground, there is broken ground, there is enclosed ground, there is deadly ground. When the lords fight in their own territory, it is scattering ground. When one enters others’ territory but not deeply, it is light ground. Where it is advantageous for us to take it and advantageous for them to take it, it is contested ground. Where we can go and they can come, it is connecting ground. Where the territories of three lords meet, and whoever arrives first wins the multitudes of all under Heaven, it is crossroads ground. When one has entered deep into others’ territory, with many walled cities and towns at one’s back, it is heavy ground. Mountains and forests, precipices and defiles, marshes and wetlands—all roads hard to travel—are broken ground. Where the way in is narrow and the way back is roundabout, so that their few can strike our many, it is enclosed ground. Where those who fight quickly survive and those who do not fight quickly perish, it is deadly ground. For this reason, on scattering ground, do not fight; on light ground, do not stop; on contested ground, do not attack; on connecting ground, do not be cut off; on crossroads ground, join with allies; on heavy ground, plunder; on broken ground, keep moving; on enclosed ground, make plans; on deadly ground, fight.

Those the ancients called skilled at using troops could keep the enemy’s front and rear from reaching each other, the many and the few from relying on each other, the noble and the humble from rescuing each other, those above and those below from holding together. The enemy’s soldiers scattered and did not gather; when the troops came together, they were not in order. They moved when it accorded with advantage and stopped when it did not.

May I ask: “If the enemy comes in great numbers and good order, how should we meet them?” Answer: “First seize what they love most, and they will listen.” It is the nature of war that speed governs everything. Exploit what others cannot reach in time, travel by routes they have not anticipated, and strike where they have set no watch.

As a rule, this is the way of an invading army: go in deep, and the troops are united, and the defenders cannot overcome them. Plunder the rich countryside, and the whole army has enough to eat. Take care to nourish them and do not wear them out. Unite their spirit and build up their strength. Move the troops and lay plans so that you cannot be fathomed. Throw them where there is nowhere to go, and they will die before they run. When death is the price, what will they not accomplish? Officers and soldiers will give everything they have. When soldiers are deeply trapped, they do not fear. When there is nowhere to go, they hold firm. When they are deep inside, they hold together. When there is no choice, they fight. For this reason the troops are on guard without being drilled, deliver without being asked, are loyal without being pledged, and are faithful without being ordered. Ban omen-reading and dispel doubts, and until death they will go nowhere else. If our officers keep no wealth to spare, it is not because they scorn riches; if they keep no life to spare, it is not because they scorn long life. On the day the orders go out, those soldiers who are sitting wet their collars with tears, and those lying flat have tears meeting under their chins. Throw them where there is nowhere to go, and they will have the courage of Zhuan Zhu and Cao Gui.note

So those skilled at using troops are like the Shuairan. The Shuairan is a snake of Mount Chang. Strike its head, and its tail comes. Strike its tail, and its head comes. Strike its middle, and head and tail both come.note

The business of the general is to be calm and inscrutable, upright and disciplined. The general can keep the eyes and ears of the officers and soldiers in the dark, so that they know nothing. The general changes the undertakings and revises the plans, so that no one grasps them. The general moves the camp and winds the route, so that no one can work out the intent. When the commander sets the decisive moment for them, it is like sending them up high and removing the ladder. When the commander leads them deep into the lands of the other lords and releases the trigger, it is like herding a flock of sheep: driven this way, driven that way, no one knows where they are going. To gather the whole army and throw it into danger—this is the business of the general. The variations of the nine grounds, the advantages of drawing in and stretching out, the patterns of human feeling—these must be examined with care.

As a rule, this is the way of an invading army: deep in, the troops are united; shallow in, they scatter. Leaving your state and crossing the border with an army—this is cut-off ground. Open on all four sides—this is crossroads ground. Deep inside—this is heavy ground. Shallow inside—this is light ground. Strongholds behind and narrows in front—this is enclosed ground. Nowhere to go—this is deadly ground. For this reason, on scattering ground, I will unify their will. On light ground, I will keep them connected. On contested ground, I will press my rear units forward. On connecting ground, I will guard with care. On crossroads ground, I will strengthen my alliances. On heavy ground, I will keep the food coming. On broken ground, I will advance along the route. On enclosed ground, I will block the gaps. On deadly ground, I will show them there is no living through it. So the nature of troops is this: when surrounded, they resist; when there is no choice, they fight; when pushed past the limit, they obey.

For this reason, one who does not know the plans of the other lords cannot form alliances in advance; one who does not know the form of mountains and forests, precipices and defiles, marshes and wetlands cannot march an army; one who does not use local guides cannot gain the advantages of the ground. An army ignorant of even one of these four or five things is not the army of a hegemon or a king. When the army of a hegemon or a king attacks a great state, that state cannot gather its forces. When its might is brought to bear on the enemy, the enemy’s alliances cannot come together. For this reason it does not contend for alliances with all under Heaven, nor build up power in all under Heaven. It relies on its own resources and brings its might to bear on the enemy. So the enemy’s cities can be taken and the enemy’s state overthrown. Bestow rewards beyond the regulations; issue orders beyond the usual rules. Put the whole army to work as if employing one person. Set them to work with tasks; do not explain in words. Set them to work with advantages; do not tell them of the harm. Throw them into ground of ruin, and then they survive; sink them into deadly ground, and then they live. Only when the troops have fallen into harm can they decide victory and defeat.

The business of waging war lies in going along with the enemy’s intentions and studying them with care. Concentrate your strength in one direction, and a thousand li away you kill their general. This is called achieving things by skill.

For this reason, on the day the campaign is launched, close the passes, snap the tallies, and allow no envoys through. In the halls of the temple, be rigorous, so as to bring the matter to its end. If the enemy leaves an opening, you must get in quickly. Make what they love your first target, and quietly fix the time to meet them. Keep to the carpenter’s ink line yet follow the enemy, so as to settle the battle. For this reason, at first be like a maiden, and the enemy will open the door; afterward be like a running hare, and the enemy will have no time to resist.

Sunzi said: In general, fire attacks are of five kinds. The first is burning people. The second is burning stores. The third is burning baggage trains. The fourth is burning arsenals. The fifth is burning supply lines. Using fire requires the right means, and the materials for fire must always be at hand. Setting fires has its season; starting them has its days. The season: when the air is dry. The days: when the moon is in the lodges Ji, Bi, Yi and Zhen. These four lodges bring days when the wind gets up.note

In general, in fire attacks, you must respond to the five variations of fire. When fire starts within their camp, answer it early from outside. If fire starts but their troops keep quiet, hold back and do not attack. Let the fire reach its full force; follow up if you can, and stop if you cannot. When fire can be started from outside, do not wait for it inside; start it at the right time. When fire is started upwind, do not attack from downwind. By day the wind blows long; at night it stops.

Every army must know the five variations of fire and watch for the right days by calculation. So those who back an attack with fire are clear-sighted; those who back an attack with water are strong. Water can cut off, but it cannot seize.

To win battles and take what you attack, yet not secure the achievement, is disastrous. This is called “wasteful delay.” So it is said: The enlightened ruler considers it; the good general carries it through. Without advantage, do not move. Without gain, do not deploy. Without danger, do not fight. The ruler must not raise an army out of anger; the general must not join battle out of resentment. Move when it accords with advantage; stop when it does not. Anger can turn back into joy; resentment can turn back into pleasure. But a state that perishes cannot be brought back into being, and the dead cannot live again. So it is said: The enlightened ruler is careful about this; the good general is wary of it. This is the way to keep the state safe and the army whole.note

Sunzi said: As a rule, when you raise an army of a hundred thousand and march a thousand li, the expenses of the people and the outlays of the state come to a thousand pieces of gold a day. There is upheaval at home and abroad; people are worn out on the roads; and seven hundred thousand households cannot attend to their work. The two sides hold out against each other for years, all to fight over a single day’s victory. To begrudge ranks, salaries and a hundred pieces of gold, and so not know the enemy’s situation, is inhumanity at its worst. Such a one is not a general for the people, not a helper to the ruler, not the one who commands victory. So what lets the enlightened ruler and the worthy general move and overcome others, with achievements that stand out above the crowd, is foreknowledge. Foreknowledge cannot be obtained from ghosts and spirits, cannot be inferred from comparable events, cannot be verified by measurement. It must come from people—from those who know the enemy’s situation.

So there are five kinds of spies to use: there are local spies, there are inside spies, there are double agents, there are expendable spies, there are returning spies. When all five are set in motion together and no one knows their workings, this is called “the divine thread.” It is the treasure of the ruler.note

Local spies: we use the people of the enemy’s localities. Inside spies: we use the enemy’s officials. Double agents: we use the enemy’s own spies. Expendable spies: we create false information outside, let our spies know it, and have them pass it to the enemy state. Returning spies: they come back to report.

So in all the affairs of the army, none are closer to the general than the spies, no rewards are richer than those for spies, no matters are more secret than those of spies. Without sagely wisdom, one cannot use spies. Without humaneness and righteousness, one cannot direct spies. Without subtlety, one cannot get the truth from spies. Subtle indeed! Subtle indeed! There is nothing for which spies are not used. If a spy’s mission is heard of before it is launched, the one who heard of it and those who were told are all put to death.

As a rule, for an army you wish to strike, a city you wish to attack, a person you wish to kill, you must first know the names of the commanding general, the attendants, the ushers, the gatekeepers and the retainers. Have our spies seek them out and learn them. You must seek out the enemy agents sent to spy on us, profit them, lead them on and give them quarters; so double agents can be obtained and used. Through this we know, so local spies and inside spies can be obtained and used. Through this we know, so expendable spies can carry false information and be made to tell the enemy. Through this we know, so returning spies can be made to return as planned. The ruler must know the affairs of the five kinds of spies. Knowing them depends on the double agent. So the double agent must be treated generously.

In the past, when Yin rose, Yi Zhi was in Xia. When Zhou rose, Lü Ya was in Shang. So the enlightened ruler and the worthy general who can make people of superior intelligence their spies will surely achieve great things. This is the essence of warfare, what the whole army relies on in every move.note