Sun Tzu on the Art of War: Weak Points and Strong 
Weak Points and Strong 
Sun Tzu said: Whoever is first in the field and awaits the coming of the enemy, will be fresh for the fight; whoever is second in the field and has to hasten to battle will arrive exhausted.
Therefore the clever combatant imposes his will on the enemy, but does not allow the enemy's will to be imposed on him. 
By holding out advantages to him, he can cause the enemy to approach of his own accord; or, by inflicting damage, he can make it impossible for the enemy to draw near. 
If the enemy is taking his ease, he can harass him;  if well supplied with food, he can starve him out; if quietly encamped, he can force him to move.
Appear at points which the enemy must hasten to defend; march swiftly to places where you are not expected.
An army may march great distances without distress, if it marches through country where the enemy is not. 
Hence that general is skillful in attack whose opponent does not know what to defend; and he is skillful in defense whose opponent does not know what to attack. 
O divine art of subtlety and secrecy! Through you we learn to be invisible, through you inaudible;  and hence we can hold the enemy's fate in our hands.
You may advance and be absolutely irresistible, if you make for the enemy's weak points; you may retire and be safe from pursuit if your movements are more rapid than those of the enemy.
If we wish to fight, the enemy can be forced to an engagement even though he be sheltered behind a high rampart and a deep ditch. All we need do is attack some other place that he will be obliged to relieve. 
If we do not wish to fight, we can prevent the enemy from engaging us even though the lines of our encampment be merely traced out on the ground. All we need do is to throw something odd and unaccountable in his way. 
By discovering the enemy's dispositions and remaining invisible ourselves, we can keep our forces concentrated, while the enemy's must be divided. 
We can form a single united body, while the enemy must split up into fractions. Hence there will be a whole pitted against separate parts of a whole, which means that we shall be many to the enemy's few.
And if we are able thus to attack an inferior force with a superior one, our opponents will be in dire straits.
The spot where we intend to fight must not be made known; for then the enemy will have to prepare against a possible attack at several different points;  and his forces being thus distributed in many directions, the numbers we shall have to face at any given point will be proportionately few.
For should the enemy strengthen his van, he will weaken his rear; should he strengthen his rear, he will weaken his van; should he strengthen his left, he will weaken his right; should he strengthen his right, he will weaken his left. If he sends reinforcements everywhere, he will everywhere be weak. 
Numerical weakness comes from having to prepare against possible attacks; numerical strength, from compelling our adversary to make these preparations against us. 
Knowing the place and the time of the coming battle, we may concentrate from the greatest distances in order to fight. 
But if neither time nor place be known, then the left wing will be impotent to succor the right, the right equally impotent to succor the left, the van unable to relieve the rear, or the rear to support the van. How much more so if the furthest portions of the army are anything under a hundred LI apart, and even the nearest are separated by several LI! 
Though according to my estimate the soldiers of Yueh exceed our own in number, that shall advantage them nothing in the matter of victory. I say then that victory can be achieved. 
Though the enemy be stronger in numbers, we may prevent him from fighting. Scheme so as to discover his plans and the likelihood of their success. 
Rouse him, and learn the principle of his activity or inactivity.  Force him to reveal himself, so as to find out his vulnerable spots.
Carefully compare the opposing army with your own, so that you may know where strength is superabundant and where it is deficient. 
In making tactical dispositions, the highest pitch you can attain is to conceal them;  conceal your dispositions, and you will be safe from the prying of the subtlest spies, from the machinations of the wisest brains. 
How victory may be produced for them out of the enemy's own tactics-that is what the multitude cannot comprehend.
All men can see the tactics whereby I conquer, but what none can see is the strategy out of which victory is evolved. 
Do not repeat the tactics which have gained you one victory, but let your methods be regulated by the infinite variety of circumstances. 
Military tactics are like unto water; for water in its natural course runs away from high places and hastens downwards.
So in war, the way is to avoid what is strong and to strike at what is weak. 
Water shapes its course according to the nature of the ground over which it flows; the soldier works out his victory in relation to the foe whom he is facing.
Therefore, just as water retains no constant shape, so in warfare there are no constant conditions.
He who can modify his tactics in relation to his opponent and thereby succeed in winning, may be called a heaven- born captain.
The five elements (water, fire, wood, metal, earth) are not always equally predominant;  the four seasons make way for each other in turn.  There are short days and long; the moon has its periods of waning and waxing. 
|||Chang Yu attempts to explain the sequence of chapters as follows: "Chapter IV, on Tactical Dispositions, treated of the offensive and the defensive; chapter V, on Energy, dealt with direct and indirect methods. The good general acquaints himself first with the theory of attack and defense, and then turns his attention to direct and indirect methods. He studies the art of varying and combining these two methods before proceeding to the subject of weak and strong points. For the use of direct or indirect methods arises out of attack and defense, and the perception of weak and strong points depends again on the above methods. Hence the present chapter comes immediately after the chapter on Energy."|
One mark of a great soldier is that he fight on his own terms or fights not at all. [See Col. Henderson's biography of Stonewall Jackson, 1902 ed., vol. II, p. 490.]
In the first case, he will entice him with a bait; in the second, he will strike at some important point which the enemy will have to defend.
This passage may be cited as evidence against Mei Yao- Ch`en's interpretation of I. ss. 23.
Ts`ao Kung sums up very well: "Emerge from the void [q.d. like "a bolt from the blue"], strike at vulnerable points, shun places that are defended, attack in unexpected quarters."
Wang Hsi explains "undefended places" as "weak points; that is to say, where the general is lacking in capacity, or the soldiers in spirit; where the walls are not strong enough, or the precautions not strict enough; where relief comes too late, or provisions are too scanty, or the defenders are variance amongst themselves."
I.e., where there are none of the weak points mentioned above. There is rather a nice point involved in the interpretation of this later clause. Tu Mu, Ch`en Hao, and Mei Yao-ch`en assume the meaning to be: "In order to make your defense quite safe, you must defend EVEN those places that are not likely to be attacked;" and Tu Mu adds: "How much more, then, those that will be attacked." Taken thus, however, the clause balances less well with the preceding-always a consideration in the highly antithetical style which is natural to the Chinese. Chang Yu, therefore, seems to come nearer the mark in saying: "He who is skilled in attack flashes forth from the topmost heights of heaven [see IV. ss. 7], making it impossible for the enemy to guard against him. This being so, the places that I shall attack are precisely those that the enemy cannot defend.... He who is skilled in defense hides in the most secret recesses of the earth, making it impossible for the enemy to estimate his whereabouts. This being so, the places that I shall hold are precisely those that the enemy cannot attack."
An aphorism which puts the whole art of war in a nutshell.
Literally, "without form or sound," but it is said of course with reference to the enemy.
Tu Mu says: "If the enemy is the invading party, we can cut his line of communications and occupy the roads by which he will have to return; if we are the invaders, we may direct our attack against the sovereign himself." It is clear that Sun Tzu, unlike certain generals in the late Boer war, was no believer in frontal attacks.
This extremely concise expression is intelligibly paraphrased by Chia Lin: "even though we have constructed neither wall nor ditch." Li Ch`uan says: "we puzzle him by strange and unusual dispositions;" and Tu Mu finally clinches the meaning by three illustrative anecdotes-one of Chu-ko Liang, who when occupying Yang-p`ing and about to be attacked by Ssu-ma I, suddenly struck his colors, stopped the beating of the drums, and flung open the city gates, showing only a few men engaged in sweeping and sprinkling the ground. This unexpected proceeding had the intended effect; for Ssu-ma I, suspecting an ambush, actually drew off his army and retreated. What Sun Tzu is advocating here, therefore, is nothing more nor less than the timely use of "bluff."
The conclusion is perhaps not very obvious, but Chang Yu (after Mei Yao-ch`en) rightly explains it thus: "If the enemy's dispositions are visible, we can make for him in one body; whereas, our own dispositions being kept secret, the enemy will be obliged to divide his forces in order to guard against attack from every quarter."
Sheridan once explained the reason of General Grant's victories by saying that "while his opponents were kept fully employed wondering what he was going to do, HE was thinking most of what he was going to do himself."
In Frederick the Great's INSTRUCTIONS TO HIS GENERALS we read: "A defensive war is apt to betray us into too frequent detachment. Those generals who have had but little experience attempt to protect every point, while those who are better acquainted with their profession, having only the capital object in view, guard against a decisive blow, and acquiesce in small misfortunes to avoid greater."
The highest generalship, in Col. Henderson's words, is "to compel the enemy to disperse his army, and then to concentrate superior force against each fraction in turn."
What Sun Tzu evidently has in mind is that nice calculation of distances and that masterly employment of strategy which enable a general to divide his army for the purpose of a long and rapid march, and afterwards to effect a junction at precisely the right spot and the right hour in order to confront the enemy in overwhelming strength. Among many such successful junctions which military history records, one of the most dramatic and decisive was the appearance of Blucher just at the critical moment on the field of Waterloo.
The Chinese of this last sentence is a little lacking in precision, but the mental picture we are required to draw is probably that of an army advancing towards a given rendezvous in separate columns, each of which has orders to be there on a fixed date. If the general allows the various detachments to proceed at haphazard, without precise instructions as to the time and place of meeting, the enemy will be able to annihilate the army in detail. Chang Yu's note may be worth quoting here: "If we do not know the place where our opponents mean to concentrate or the day on which they will join battle, our unity will be forfeited through our preparations for defense, and the positions we hold will be insecure. Suddenly happening upon a powerful foe, we shall be brought to battle in a flurried condition, and no mutual support will be possible between wings, vanguard or rear, especially if there is any great distance between the foremost and hindmost divisions of the army."
Alas for these brave words! The long feud between the two states ended in 473 B.C. with the total defeat of Wu by Kou Chien and its incorporation in Yueh. This was doubtless long after Sun Tzu's death. With his present assertion compare IV. ss. 4. Chang Yu is the only one to point out the seeming discrepancy, which he thus goes on to explain: "In the chapter on Tactical Dispositions it is said, 'One may KNOW how to conquer without being able to DO it,' whereas here we have the statement that 'victory' can be achieved.' The explanation is, that in the former chapter, where the offensive and defensive are under discussion, it is said that if the enemy is fully prepared, one cannot make certain of beating him. But the present passage refers particularly to the soldiers of Yueh who, according to Sun Tzu's calculations, will be kept in ignorance of the time and place of the impending struggle. That is why he says here that victory can be achieved."
An alternative reading offered by Chia Lin is: "Know beforehand all plans conducive to our success and to the enemy's failure."
Chang Yu tells us that by noting the joy or anger shown by the enemy on being thus disturbed, we shall be able to conclude whether his policy is to lie low or the reverse. He instances the action of Cho-ku Liang, who sent the scornful present of a woman's head-dress to Ssu-ma I, in order to goad him out of his Fabian tactics.
Cf. IV. ss. 6.
The piquancy of the paradox evaporates in translation. Concealment is perhaps not so much actual invisibility (see supra ss. 9) as "showing no sign" of what you mean to do, of the plans that are formed in your brain.
Tu Mu explains: "Though the enemy may have clever and capable officers, they will not be able to lay any plans against us."
I.e., everybody can see superficially how a battle is won; what they cannot see is the long series of plans and combinations which has preceded the battle.
As Wang Hsi sagely remarks: "There is but one root- principle underlying victory, but the tactics which lead up to it are infinite in number." With this compare Col. Henderson: "The rules of strategy are few and simple. They may be learned in a week. They may be taught by familiar illustrations or a dozen diagrams. But such knowledge will no more teach a man to lead an army like Napoleon than a knowledge of grammar will teach him to write like Gibbon."
Like water, taking the line of least resistance.
That is, as Wang Hsi says: "they predominate alternately."
Literally, "have no invariable seat."
Cf. V. ss. 6. The purport of the passage is simply to illustrate the want of fixity in war by the changes constantly taking place in Nature. The comparison is not very happy, however, because the regularity of the phenomena which Sun Tzu mentions is by no means paralleled in war.