《孫子註解》Vol. 6

The "Vacuity and Substance" chapter of Sunzi's Art of War discusses the flexible application of shifting between weak and strong positions in warfare. Cao Cao notes the key lies in discerning the relative strengths and weaknesses of both sides. Li Quan adds that skilled commanders can transform apparent weakness into real strength, then turn solid defenses into vulnerabilities when attacking. Du Mu emphasizes that military operations should avoid enemy strongholds and strike at weak points, requiring thorough understanding of relative positions. Wang Xi and Zhang Yu further explain that defenses should be solid while attacks must be unpredictable.

Sunzi states that the side which first occupies advantageous terrain to await the enemy maintains ease ("yi" denoting comfort), while those arriving late to battle become fatigued. Both Cao Cao and Li Quan observe that early arrivals preserve their forces' vitality. Jia Lin clarifies that armies securing positional advantages prepare thoroughly, allowing troops and horses to rest. Du You and Wang Xi concur, with Zhang Yu adding that controlling strategic locations beforehand forces the enemy to attack while one's own forces remain fresh.

Late arrivals inevitably suffer exhaustion. Li Quan employs "Taiyi Dunjia" (an ancient military divination method) to illustrate: the attacking side is "guest," the defending side "host," and defense is always easier than offense. Du Mu cites a historical example where Northern Zhou troops attacked Northern Qi after heavy snowfall. Qi general Duan Shao deliberately withheld engagement until Zhou infantry were exhausted struggling through snowdrifts, securing decisive victory. Jia Lin proposes an alternative tactic: when enemies hold superior positions, feign retreat to lure them into abandoning their advantage, thereby transferring fatigue to them. Meng Shi shares similar views.

This passage primarily expounds the tactical principle of "awaiting the exhausted at ease," stressing the importance of securing favorable positions early while demonstrating through case studies how terrain and strategy can be leveraged to wear down opponents.

When the enemy has already occupied advantageous terrain, and our army must march long distances to contend for position, both soldiers and horses will be exhausted—placing us at a severe disadvantage in battle.

Mei Yaochen explains: The side that arrives first at the battlefield can conserve strength while awaiting the fatigued enemy, maintaining combat readiness. The side that arrives later, forced to engage hastily, will be weakened. A classic example comes from the Warring States period: When the Qin army attacked Han and besieged the city of Yanyu, Zhao sent General Zhao She to relieve it. His strategist Xu Li advised: "The Qin forces did not expect Zhao’s troops to arrive so swiftly—their morale is still high. You must concentrate your forces and hold firm positions; otherwise, we will surely be defeated." He further suggested seizing the high ground of North Mountain first: "Those who occupy North Mountain first will prevail; those who arrive later will fail." Zhao She immediately dispatched ten thousand troops to secure the mountain. When the Qin army arrived belatedly and failed to take the heights, Zhao She launched a full assault, crushing the Qin forces and lifting the siege.

A similar case occurred in the early Eastern Han dynasty: After generals campaigning against the rebel Wei Xiao were defeated, Emperor Guangwu ordered a retreat to Xunyi. Wei Xiao, emboldened by victory, sent Wang Yuan and Xing Xun with over twenty thousand troops to attack Longxi, while splitting forces to assault Xunyi. Han general Feng Yi sought to occupy Xunyi first, but other commanders protested: "The enemy has just triumphed—their morale is soaring. We should avoid direct confrontation, rest our troops, and plan carefully." Feng Yi countered: "The enemy is advancing aggressively. If they take Xunyi, the entire Sanfu region will be shaken. Attack is less favorable than defense—let us seize the city first, conserve our strength, and await their exhaustion rather than face them head-on." He then secretly entered Xunyi, concealing banners and silencing drums. When Xing Xun arrived unaware, Feng Yi suddenly unleashed a barrage of drums and banners, throwing the enemy into panic and routing them in a decisive pursuit.

During the Eastern Wei’s campaign against Western Wei, General Gao Huan (later Emperor Shenwu of Qi) crossed the Pujin and Luo Rivers, reaching Xu Yuan. Western Wei’s Yuwen Tai (Emperor Wen of Zhou) advanced to Shayuan to intercept him. Learning of Yuwen Tai’s approach, Gao Huan immediately mobilized for battle. The next day, scouts reported the imminent arrival of Gao Huan’s main force. Western Wei general Li Bi advised: "We are outnumbered—we cannot deploy on open ground. The bend of the Wei River ten li east offers superior terrain; we must secure it first." The Western Wei army thus formed up with their backs to the river at Wei Qu and crushed the Eastern Wei forces.

Zhang Yu concludes: When the enemy holds favorable terrain and we must rush to engage, exhaustion will inevitably cripple our combat effectiveness. Therefore, the superior strategy is to arrive first at the chosen battleground, fortify positions, and await the enemy in full readiness.

When the enemy has already deployed their battle formations while our forces have just arrived at the battlefield, we will inevitably fall into passivity. This resembles the historical example where the Song army had already completed their formations while the Chu troops hadn't fully crossed the river. Therefore, those skilled in warfare must maneuver the enemy rather than be maneuvered by them.

Li Quan explains that this method exhausts the enemy through forced marches while maintaining our own initiative. Du Mu cites the example of Geng Yan from the Eastern Han: When Fei Yi, general under Zhang Bu, divided his forces to garrison Julu, Geng Yan feigned preparations for a full-scale assault—ostentatiously making arrangements to fill in the moats. When Fei Yi arrived with thirty thousand elite reinforcements, Geng Yan ambushed them from high ground, crushing the enemy forces and killing Fei Yi in one stroke.

Du You supplements that when two armies are distant, we should make the enemy take risks to attack while securing advantageous terrain ourselves. Mei Yaochen and Wang Xi both emphasize that forcing the enemy to exhaust themselves allows us to await them in comfort. He and Zhang Yu point out that luring the enemy into battle lets us control the initiative, just as Geng Yan used Julu as bait to maneuver Fei Yi.

As for making the enemy come voluntarily, the key lies in tempting them with advantages. Both Cao Cao and Li Quan advocate using benefits to entice the enemy, similar to Li Mu's strategy against the Xiongnu during the Warring States period. Du Mu provides specifics: Li Mu intentionally allowed large herds to graze openly. When small Xiongnu raiding parties attacked, he feigned retreat—using several thousand men as bait to lure the Chanyu into his trap.

Li Mu led his army to a decisive victory over the Xiongnu at Muye, slaughtering 100,000 cavalry. After the Xiongnu chanyu (chieftain) fled, they dared not invade the border for over a year. Mei Yaochen explained: Why would enemies come voluntarily? They must be lured by advantage. He Shi added: By tempting enemies with gain, we can await them at our ease while they exhaust themselves. Zhang Yu noted: The key to making enemies come lies in baiting them with benefits—like when Li Mu feigned retreat to lure the Xiongnu, or when Yang Su destroyed his own chariots to entice the Turks.

To prevent enemies from advancing, strike their vital points. Cao Cao advised: "Attack where the enemy must rescue." Li Quan cited the Warring States example: When Wei attacked Zhao's Handan, Qi general Tian Ji wanted to reinforce directly, but strategist Sun Bin argued: "Untangling knots shouldn't involve brute force, nor stopping fights through direct confrontation. Strike where the enemy is vulnerable—Wei will surely withdraw to defend itself, thus saving Zhao while exhausting Wei." The Wei army indeed abandoned Handan to rescue Daliang, only to be ambushed and crushed by Qi forces at Maling. Du Mu cited Cao Cao's campaign: When bandits attacked Wuyang, Cao struck their stronghold instead, forcing their retreat before crushing them. Chen Hao referenced Wu Zixu's harassment of Chu and Sun Bin's defeat of Wei. Du You summarized: "Control the vital point—like a cat guarding a hole keeps ten thousand mice at bay, or a tiger by a stream stops ten thousand deer." Mei Yaochen and Wang Xi emphasized making enemies fear for their vitals. Zhang Yu concluded: "Sun Bin lifting the siege of Handan by threatening Daliang exemplifies this principle."

To exhaust well-rested enemies, keep them constantly moving. Cao Cao advocated harassing opponents through varied tactics. Li Quan proposed sudden, unpredictable strikes to deny them peace.

This passage discusses ancient military strategies for gaining advantage by exhausting an enemy's physical strength and resources.

Du Mu cites the strategy of Gao Jiong from the Sui dynasty in conquering the Chen state: By exploiting the difference in harvest times between northern and southern regions, they would feign attacks just before the Jiangnan region's crops ripened, forcing the enemy to mobilize troops for defense and miss farming seasons. When the enemy fully assembled, they would withdraw. Repeating this several times left the enemy utterly exhausted.

Mei Yaochen and Wang Xi both emphasize the importance of continuously harassing the enemy to deny them rest. He Shi references Wu Zixu's Spring and Autumn period advice: Divide forces into three rotating units to harass Chu state troops until they were exhausted, after which Wu launched a major offensive that ultimately captured the Chu capital.

Zhang Yu summarizes that one should employ various methods to mislead and wear down the enemy. If the enemy awaits battle while rested, avoid direct engagement—compel them to move until their initial advantage turns to exhaustion.

Regarding the "well-fed can be starved" tactic:

Cao Cao advocates cutting enemy supply lines. Li Quan proposes burning enemy grain stores. Du Mu adds that when campaigning abroad, one could imitate Gao Jiong's Sui dynasty tactic—sending operatives to torch Jiangnan's thatched bamboo dwellings (where grain was typically stored above ground in this region) during windy conditions. Repeating such strikes would deplete enemy resources. Similarly, Sima Yi during the Three Kingdoms period calculated enemy grain consumption to formulate strategy.

The core principle of these tactics lies in transforming the enemy's advantages into disadvantages through systematic exhaustion of their physical stamina and material resources, thereby securing ultimate victory.

This passage recounts classic military cases from ancient warfare where victory was achieved by cutting off enemy supply lines. The core strategy involved starving the opposing forces into weakness before launching decisive attacks.

The first story describes Sima Shi (Emperor Jing of Jin) during the Three Kingdoms period using deception to lull his enemies into complacency. By feigning weakness, he tricked Zhuge Dan's troops into believing victory was assured, only to conquer their city after their provisions were exhausted. Similarly, during the late Sui dynasty, Li Mi pretended to seek peace negotiations with Yuwen Huaji, deliberately prolonging the process to deplete enemy supplies—Yuwen's forces eventually collapsed when their food ran out.

In the Han dynasty, Zhou Yafu employed the "sacrificing Liang" strategy against the Wu-Chu alliance. He deliberately abandoned Liang territory to instead sever enemy grain routes. After concentrating his forces at Xingyang, Zhou retreated to Changyi where he fortified deep trenches and high ramparts, deploying light cavalry to cut off the Wu-Chu army's rear supply lines. Starving and unable to provoke battle, the enemy forces attempted retreat but were crushed in pursuit.

During Emperor Gengshi's reign, Liu Bosheng (elder brother of Emperor Guangwu Liu Xiu) faced a 100,000-strong army led by Zhen Fu and Liang Qiuci. Feigning retreat, he secretly dispatched troops to raid the enemy's supply depot at Lanxiang under cover of darkness. Deprived of provisions, the opposing forces were routed the next day by coordinated attacks from north and south.

When Tang general Fu Gongshi garrisoned troops at Bowang Mountain, opposing commander Wang Xiaogong adopted a strategy of fortified defense without engagement. These historical examples collectively demonstrate a fundamental principle: avoiding direct confrontation when enemies are well-provisioned, then striking decisively after their supply lines are cut and morale collapses.

[Note: "Sacrificing Liang" refers to deliberately abandoning Liang territory; "fortified defense" indicates trench-and-rampart tactics; "supply trains" denote military provisions and equipment. These cases exemplify Sun Tzu's Art of War principle of "living off the enemy," emphasizing how controlling grain supply determines battlefield outcomes.]

This passage discusses the ancient military strategy of "attacking what the enemy must rescue" (攻其必救).

When enemy forces refuse to engage in battle, one can strike at vital positions they are certain to defend, forcing them to come out and fight. As Cao Cao observed, by targeting places the enemy values most and advancing toward positions they must protect, the enemy will have no choice but to respond.

Li Quan further elaborates that the attack should be unexpected, directed at what the enemy holds dearest. Du Mu cites the example of Sima Yi’s campaign against Gongsun Yuan: when Gongsun Yuan entrenched himself behind the natural barrier of the Liao River in Liaodong, Sima Yi bypassed the defenses and directly attacked Xiangping (Gongsun Yuan’s stronghold), compelling the enemy to abandon their defensive position and engage in battle—resulting in a decisive victory.

Chen Hao references a historical case from the Spring and Autumn period: when the state of Jin sought to attack Chu, it first seized control of Cao, an ally of Chu, and redistributed Cao’s territory to Song. Since Chu was certain to come to Cao’s aid, this maneuver forced Chu into open conflict.

Mei Yaochen, Wang Xi, and others agree with this principle, emphasizing the need to strike where the enemy is most vulnerable. He Shi notes that when a cherished position is under attack, the enemy cannot afford to remain passive. Zhang Yu concludes that when the enemy insists on holding their ground, the key is to identify and assault the critical points they must defend, thereby compelling them to act.

The core of this tactic lies in shifting from passivity to initiative—by threatening the enemy’s vital interests, one forces a reluctant opponent to abandon their defenses and engage on unfavorable terms.

This passage discusses the tactical application of "striking where the enemy least expects" in military strategy. When the enemy maintains tight defenses, one must choose unexpected points of attack. Cao Cao explains that this prevents the enemy from coordinating timely reinforcements. He Shi further notes that such maneuvers force the enemy to react to our movements.

Marching a thousand li without exhaustion becomes possible by advancing through undefended territory. Cao Cao states this means avoiding heavily fortified areas to strike where the enemy is unprepared. Li Quan advocates attacking vulnerable points when the enemy's guard is down. Du Mu cites the historical example of Western Wei's General Zhou Wendi conquering Shu: though the Shu region had relied on natural defenses for a century, Zhou dispatched Yuchi Jiong with elite cavalry for a lightning strike—accelerating across plains while advancing cautiously through passes—ultimately achieving total surprise by penetrating the heartland. This demonstrates how maneuvering through undefended areas maintains complete initiative, thereby preventing fatigue.

Chen Hao elaborates that "undefended" encompasses not only complete absence of preparations but also lax security, incompetent commanders, low morale, or insufficient supplies. When our disciplined forces attack, the enemy collapses without battle. Both Mei Yaochen and He Shi emphasize targeting unprepared opponents. He Shi provides two additional examples: Cao Cao's northern expedition against the Wuhuan, where Guo Jia advised a light cavalry raid that achieved decisive victory; and Tang dynasty general Li Jing's two-thousand-li crossing of uninhabited territory to subdue the Tuyuhun. These successful campaigns all validate the effectiveness of surprise attack tactics.

Emperor Taizong of Tang once remarked that Li Jing's feat of leading three thousand light cavalry deep into Turkic territory to reclaim Dingxiang in one stroke was unparalleled in history. Zhang Yu analyzed this: striking where the enemy is unprepared and attacking undefended positions allows long-distance maneuvers without exhausting troops. A classic example is Deng Ai's invasion of Shu during the Three Kingdoms period, traversing seven hundred li of uninhabited wilderness via the Yinping mountain path.

The essential principle of certain victory lies in attacking where the enemy is unguarded. Li Quan observed that enemies are most vulnerable when relaxed. Du Mu proposed the strategy of "feinting east while striking west" — making a show of force in one direction while attacking another, luring the enemy with frontal displays before striking from behind. During the Eastern Han, Zhang Bu controlled Ju County, stationing his brother Zhang Lan at Xi'an City while garrisoning another general at Linzi. Geng Yan positioned his forces between both cities, noting Xi'an's small but fortified defenses with elite troops, while Linzi appeared larger yet more vulnerable.

Geng Yan pretended to prepare a five-day assault on Xi'an, deliberately allowing captives to escape with this intelligence. Zhang Lan maintained vigilant day-and-night defenses. On the appointed day, Geng instead ordered his troops to feast at midnight and stormed Linzi at dawn. Officers like Xun Liang urged adhering to the original plan, but Geng explained: "Xi'an is prepared, while Linzi will be caught off-guard — we'll take it in one day. With Linzi fallen, Xi'an becomes isolated." This proved a masterstroke of killing two birds with one stone.

During the late Eastern Han, Zhu Jun besieged Han Zhong's Yellow Turban forces at Wan City. He constructed encircling earthworks, feigning attacks from the southwest to draw defenders while personally leading five thousand elite troops to breach the northeast corner. Han Zhong retreated to the inner city before surrendering. Chen Hao cited another example from the late Tang: when Wang Zai attacked Shangdang, he recognized Liu Zhen's reliance on Tianjing Pass's natural defenses without proper preparations. After seizing the pass, Liu lost his stronghold.

Mei Yaochen distilled the essence of "feigning south while striking north" tactics, while Wang Xi emphasized targeting vulnerabilities — whether incompetent commanders, demoralized troops, weak fortifications, lax defenses, delayed reinforcements, insufficient supplies, or unstable morale. Zhang Yu ultimately elevated the principle: truly skilled commanders move as if descending from heaven, leaving enemies completely unprepared. When opponents are bewildered, every point we attack becomes their undefended position. Geng Yan's campaign perfectly embodies this wisdom.

This military strategy discusses the essence of offensive and defensive tactics. Zhu Jun's attack on the Yellow Turbans at Linzi is but one example.

True, unshakable defense means guarding places the enemy does not intend to attack. Du Mu explains: If even areas the enemy has no plans to assault must be defended, how much more so the places they truly target? Take, for instance, the Western Han general Zhou Yafu during the suppression of the Seven States' Rebellion at Changyi. The rebels feigned an attack on the southeastern corner, yet Zhou Yafu concentrated his defenses on the northwest. Sure enough, the enemy’s elite forces later launched a fierce assault there, but due to the impregnable defenses, they failed to break through and were ultimately routed.

Several military strategists offer profound insights on this: Chen Hao argues that instead of worrying about where the enemy might not attack, one should ensure that every defense is comprehensive. The true art of warfare lies in making every position both unassailable and unbreachable. Mei Yaochen notes that when the enemy strikes the west, the east must also be guarded. Wang Zhe emphasizes that defenses must be substantial—requiring capable commanders, elite troops, sturdy fortifications, strict vigilance, ample supplies, and unified morale. Zhang Yu points out that those skilled in defense are like hidden deep beneath the earth, leaving the enemy clueless about their true strength. Zhou Yafu’s tactic of reinforcing the northwest while neglecting the southeast exemplifies this wisdom.

A true master of warfare, when attacking, leaves the enemy unsure how to defend; when defending, leaves the enemy unsure how to attack. Cao Cao states that the key lies in not revealing military intelligence. Li Quan cites the example of Eastern Wei’s Gao Huan, who meticulously prepared before besieging Ye, and Northern Zhou’s Wei Xiaokuan, who maintained strict vigilance while defending Jinzhou. Du Mu stresses that both offensive and defensive deployments must remain secret. Jia Lin adds that smooth command, loyal troops, airtight defenses, and covert movements will leave the enemy hesitant and helpless.

Mei Yaochen summarizes: Those skilled in attack conceal their plans; those skilled in defense leave no gaps. Wang Zhe further analyzes: A master of offense waits for the enemy to expose weaknesses, then strikes swiftly, leaving them unable to react; a master of defense remains flawless at all times, giving the enemy no opening. "Unsure" refers to the enemy’s complete inability to discern the strategy. He Shi remarks that the schemes of offense and defense must be unpredictable. Zhang Yu concludes: In defense, feign weakness; in attack, feign strength. This "weakness" is not true vulnerability but a ruse to lure the enemy; this "strength" is not true might but a means to intimidate them.

This passage elucidates the subtle application of shifting between substantial and insubstantial tactics in military strategy. The core principle states that truly masterful military maneuvers should remain concealed and formless, ever-changing and unpredictable, leaving the enemy completely unable to discern our offensive or defensive intentions.

Li Quan explains that the interplay between orthodox (zheng) and unorthodox (qi) tactics in the art of war contains subtleties that cannot be fully expressed in words. These miraculous transformations hold complete sway over the enemy's life and death, like a sovereign controlling destiny. Du Mu supplements this by clarifying that "subtlety" (wei) refers to the state of quiet defense, while "divine" (shen) denotes the timing of action. The enemy's survival hinges entirely on our mastery of offensive and defensive timing.

Du You further elaborates that these transformations occur with ghostly speed, leaving the enemy utterly blind to our substantial and insubstantial positions. Both Mei Yaochen and Wang Xi emphasize that because these maneuvers are formless they cannot be spied upon, and because they are silent they cannot be guarded against—only thus can we truly control the enemy's fate. He Shi provides detailed analysis of the mutual transformation principle: we must make the enemy perceive our substantial moves as insubstantial and vice versa, while accurately judging the enemy's own substantial and insubstantial positions. When attacking, we avoid their strong points to strike their weaknesses; when defending, we mislead them into attacking non-critical positions.

The most exquisite technique involves feigning attack in the east while actually preparing defenses in the west. During offense, we leave the enemy uncertain where to defend; during defense, we leave them confused about where to attack. These offensive-defensive transformations stem from applying the principles of substantial and insubstantial: when defending, we hide as if buried nine layers beneath the earth; when attacking, we strike with the sudden violence of thunder from the nine heavens. Movements should erupt unexpectedly from below or descend abruptly from above, flickering like starlight or moving like ghosts, passing through nonexistent spaces and swirling in the deepest abyss—achieving the most subtle within subtlety, the most divine within divinity.

This scripture elucidates the subtle transformations between substantial and insubstantial in military strategy, attaining a realm of divine mystery and unfathomable subtlety.

The most profound military strategy reaches such heights that even the sharpest eyes under heaven cannot discern an army's true movements, nor the keenest ears detect its actual activities. What appears substantial is in fact insubstantial; what seems audible is truly silent. It's not that there are genuinely no traces or sounds, but rather that the enemy remains incapable of perceiving them. This represents the ultimate manifestation of the interplay between the substantial and insubstantial.

Those skilled in warfare comprehend the arcane principles of these transformations, attaining this realm of divine mystery. The unskilled, however, rigidly search for superficial clues, becoming trapped in the outward appearances of military deployment. Unable to erase the traces and sounds of their troops, they inevitably reveal their positions to the enemy. This demonstrates their failure to grasp that the essence of divine strategy lies precisely in mastering these transformations between substance and insubherency.

Zhang Yu (commentator) supplements: Offensive and defensive tactics must be exquisitely subtle and mysterious, reaching the point where forms become invisible and sounds inaudible. Thus the enemy's life or death rests entirely in our hands.

When attacking, the enemy cannot resist because we strike at their vulnerable points; when withdrawing, they cannot pursue because our movements outpace their pursuit. Cao Cao emphasizes the crucial principle: attacks must seize moments of enemy laxity, while retreats require swift execution. Li Quan stresses that during withdrawal, supplies should precede the troops to create distance. Du Mu points out that by attacking the enemy's weak points to induce collapse, they naturally lose capacity for pursuit. Chen Hao counters with an example: when Cao Cao actively withdrew from besieging Zhang Xiu, Zhang's pursuit resulted in defeat—proving the key lies not in whether the enemy collapses, but in striking vulnerabilities, withdrawing when advantageous, and keeping the enemy guessing about our intentions.

This passage discusses the ancient military tactic of "striking where the enemy must defend." Several strategists emphasize targeting an opponent's vulnerabilities: when attacking, one must identify gaps in the enemy's defenses to render them powerless; when retreating, movements must be swift and decisive to prevent pursuit. The key lies in executing actions with the speed of wind and thunder, leaving the enemy no time to react.

Cao Cao and Li Quan advocated cutting off enemy supply lines, blocking retreat routes, and directly assaulting the opposing commander. Du Mu added that if acting as the attacking force (the "guest army"), one should strike straight at the enemy's core; if defending (the "host army"), securing logistical safety is paramount. Mei Yaochen and Wang Xi both argued for targeting vital points—even if the enemy refuses to engage, attacking positions they cannot afford to abandon will force them into battle.

Two historical examples illustrate this: First, during Sima Yi’s (Xuanwang) campaign against Gongsun Yuan, he feigned abandoning a frontal assault and suddenly marched straight toward the enemy’s stronghold at Xiangping. When subordinates questioned this encirclement without direct engagement, Sima Yi explained: "The enemy built high fortifications to exhaust us; by striking their heartland, we’ll panic them into battle." True to his prediction, the enemy fell into the trap and suffered three consecutive defeats. Second, during the Tang dynasty, Ma Sui faced Tian Yue’s army, which refused to fight while his own supplies dwindled. Ma Sui ordered his troops to advance with only ten days' rations, presenting an all-or-nothing stance.

The core principle of these strategies is battlefield initiative—either attacking critical points the enemy cannot ignore or creating situations that compel them to engage. By dictating the enemy’s movements rather than reacting to them, victory can be achieved at minimal cost.

Li Baozhen and Li Peng asked: "With our provisions running low yet advancing deep into enemy territory, why is this?" Ma Sui replied: "Scarce provisions precisely favor swift decisive battles. The art of war teaches us to maneuver the enemy rather than be maneuvered. Now Tian Yue has united the three armies of Ziqing and Yanzhou in mutual support, intending to exhaust our forces through protracted warfare. Were we to divide our troops to attack his flanks, our insufficient numbers would make victory unlikely, and Tian Yue would surely send reinforcements—leaving us caught between two fronts."

Ma Sui employed the tactic of "striking where the enemy must rescue." First, he ordered the construction of three pontoon bridges across the Huan River, issuing daily challenges. Tian Yue dared not engage, while the Hengzhou garrison—fearing annihilation due to their weak numbers—joined forces with him. The next day, Tian Yue set an ambush hoping to lure Ma Sui into a trap. But Ma Sui had his troops eat heartily at midnight, and at cockcrow, with drums and horns sounding, they secretly marched swiftly along the Huan River straight toward Weizhou. He left a hundred cavalrymen with firewood behind, instructing them to burn the bridges once the main army had crossed.

After advancing over ten li, Tian Yue indeed led forty thousand infantry and cavalry across the bridges in pursuit. Ma Sui ordered his men to clear a battlefield a hundred paces wide, selecting five thousand elite troops to form battle arrays. When Tian Yue's forces were exhausted from firefighting, he suddenly launched a counterattack. Tian Yue's army suffered a crushing defeat and fled in disarray, only to find the bridges destroyed. In the chaos, twenty thousand drowned, and the Ziqing army was nearly annihilated.

Zhang Yu summarized: When guest troops are short on provisions but strong in arms, while the host army has ample supplies but weaker momentum, the enemy must be compelled to fight. Even if the enemy's cities are fortified, striking their vital points can force them to abandon their defenses. Just as in the Spring and Autumn period when Jin attacked Cao and Wei to make Chu lift the siege of Song, or when Sima Yi marched straight to Xiangping to force Gongsun Yuan into battle—the principle remains the same.

This passage primarily discusses ancient military strategies of psychological warfare and tactical formations designed to bewilder enemies and deter them from initiating combat.

Cao Cao maintained that armies should avoid frequent engagements and preserve their strength. Li Quan proposed two methods for defending cities: when within one's own territory, fortify the borders; when entering enemy lands, employ the "Tianyi Dunjia" (a Daoist battle formation) and "True Man's Sealing of the Six Wu Positions" (defensive magic), marking camp boundaries by drawing lines on the ground with swords. Meng Shi explained that while such "ground-drawing defenses" appear simple, they effectively alter the enemy's psychology, making them hesitant to attack.

When enemies cannot engage us in battle, it's because we've disrupted their plans. Cao Cao emphasized the need to confuse enemy judgment by demonstrating potential gains and losses to sow doubt. Li Quan cited the example of Li Guang, Governor of Shanggu during the Han Dynasty, who deliberately removed his saddle to rest, making the Xiongnu suspect an ambush. Du Mu elaborated on several famous historical examples: Zhao Yun's "empty fort strategy" that repelled Cao Cao's forces during the Hanzhong campaign; Zhuge Liang at Yangping Pass leaving only ten thousand defenders yet opening city gates wide and sprinkling water to sweep the ground, causing Sima Yi to suspect an ambush and withdraw; and Cao Cao facing Lü Bu by deploying minimal visible troops while hiding half his forces behind embankments, making Lü Bu retreat fearing hidden traps. Chen Hao further referenced a Spring and Autumn Annals account where Zi Yuan, Prime Minister of Chu, withdrew from attacking Zheng after observing the latter's unusual defensive preparations.

These historical cases collectively demonstrate how creating illusions and disrupting enemy judgment can achieve victory without actual combat.

This passage discusses the ancient military strategy of "the Dao of the Void and the Substantial." Jia Lin points out that by deploying decoy troops in areas where the enemy fears to advance and stationing forces in advantageous terrain, even without constructing defensive fortifications, the enemy would not dare to attack. Mei Yaochen explains that this is as simple as drawing a line on the ground—by deliberately violating conventional tactics and displaying apparent advantages, the enemy is misled into hesitation and dares not advance.

Wang Xi emphasizes that the key to this strategy lies in clearly mastering the method of controlling the situation. Zhang Yu provides an example: when our side holds the home advantage with ample provisions but fewer troops, while the enemy has limited supplies but superior numbers, the best approach is to avoid direct confrontation. Even without building strong fortifications, creating illusions to confuse the enemy can deter them from attacking. He cites two historical cases: when Chu attacked Zheng, Zheng deliberately left its city gates open, causing Chu to hesitate and withdraw; and when Sima Yi advanced against Zhuge Liang, Zhuge Liang opened the city gates, lowered his banners, and silenced the drums, leading Sima Yi to suspect an ambush and retreat.

Next, the passage explains the tactic of "revealing the enemy’s form while concealing our own." Du You states that this is akin to concentrating our forces while dispersing the enemy’s. Mei Yaochen adds that by making the enemy expose their movements while we remain hidden, we force them to divide their forces in defense. Zhang Yu elaborates further: we can disguise our regular deployments as unexpected maneuvers and our unexpected maneuvers as regular deployments, using the interplay of void and substantial to keep the enemy uncertain. Once the enemy reveals their true intentions, we can concentrate our forces to counter them, while our concealed position compels the enemy to scatter their defenses across multiple fronts.

Finally, the discussion turns to the advantage of force concentration. Du You analyzes that by accurately assessing the enemy’s disposition, we can focus superior strength to attack their dispersed units, creating a situation where ten of our troops strike one of theirs. Mei Yaochen likens this to dividing the enemy’s whole into ten parts—we can always attack one part with tenfold strength. Du You concludes that precisely because we concentrate our forces, we appear strong, while the enemy, being scattered, appears weak. Zhang Yu adds that once we discern the enemy’s void and substantial aspects, we need not defend everywhere but can focus our strength in one place. Meanwhile, the enemy, unable to perceive our true disposition, must divide their defenses, allowing us to crush them one by one with overwhelming superiority.

This passage discusses the military strategy of attacking the many with the few. The core principle states: if we can force the enemy to disperse their forces for defense, then the actual number of troops we engage in battle will be reduced.

Du Mu explains that the term "restraint" here refers to numerical inferiority. We can conceal our movements by digging deep trenches and building high fortifications, leaving the enemy uncertain of our intentions. Specific tactics include: deploying light cavalry to raid undefended areas, using powerful crossbows to strike vital points; harassing the enemy unpredictably from left and right, confusing them with banners by day and disturbing them with drumbeats at night. This forces the enemy into fearful dispersion of defenses—like someone surveying a city from a height or peering through curtains—where we gain full awareness of their troop deployments while they remain baffled by our offensive and defensive strategies.

Du You elaborates that concentrated forces become strong while dispersed ones grow weak. By striking scattered weak points with concentrated strength, we achieve victory through numerical inferiority. Mei Yaochen observes that attacking dispersed enemies with focused forces means we face fewer opponents in actual combat. Wang Zhe emphasizes creating multiple feints to misdirect enemy preparations, ensuring their actual defenses remain thin where we intend to strike.

Regarding operational secrecy: The enemy must remain utterly clueless about our movements, unaware of our intended attack routes (Du You). This compels them to fragment their forces across all possible fronts (Mei Yaochen). Cao Cao notes that concealing true intentions sows confusion that fractures enemy concentration, reducing the actual forces we confront. Zhang Yu concludes that when the enemy cannot discern whether our infantry or cavalry will strike where, they must disperse defenses—ultimately weakening their strength through division, allowing our concentrated forces to defeat isolated enemy units one by one.

This passage elucidates the core military principle of "concentrating superior forces." In modern terms:

When you concentrate troops at the front, the rear becomes vulnerable; concentrate them at the rear, and the front becomes exposed. The same logic applies to the flanks. Attempting to defend everywhere inevitably leads to dispersed and weakened forces across all positions. As Du You observed, the more directions an enemy must guard against, the more their forces become fragmented and diminished.

Mei Yaochen succinctly summarized: passive defense leads to force dispersion, while active offense compels the enemy to exhaust themselves responding. Cao Cao noted that concealing true intentions creates enemy confusion, forcing them to divide their defenses. Both Li Quan and Du Mu emphasized operational secrecy—when the enemy cannot discern our main assault direction, they must fragment their forces to guard all positions.

A fundamental principle emerges here: dispersed forces become weak (寡), while concentration creates superiority (众). Meng Shi stated it plainly: passive protection leads to dispersion, while active offense compels enemy division. Wang Xi added that attempting to defend all sides simultaneously renders all sides vulnerable.

The subsequent discussion highlights the critical importance of "knowing the battleground and the day of engagement." Cao Cao advocated using strategy to control battlefield gaps and decisive moments. Li Quan provided two cautionary examples: Cao Cao's defeat at Red Cliffs due to unfamiliarity with naval warfare, and Prince Liu Bi of Wu's failure through reckless advancement without understanding terrain. Conversely, mastery of ancient military divination techniques like Taiyi Dunjia to calculate the Three Gates and Five Generals (factors of celestial timing, terrain advantage, and human harmony) could secure victory even in distant campaigns. Du Mu cited Emperor Wu of Song's victories achieved through precise battlefield anticipation.

In essence, this passage articulates the military wisdom of "concentrating superior forces": compel the enemy to disperse their defenses by obscuring your main thrust, while accurately determining the time and place of decisive engagement to deliver concentrated strikes. This mirrors the modern warfare principle of "concentrating superior forces to destroy the enemy piecemeal."

This passage recounts Liu Yu (Emperor Wu of Song)'s military strategy during his campaign against Qiao Zong in Shu territory, along with later military theorists' discussions on "knowing the battlefield and knowing the day of battle."

When Liu Yu dispatched Zhu Lingshi to suppress Qiao Zong in Shu, he analyzed: "Previously, Liu Jingxuan attacked Huangwu via the Inner River (Min River) but failed. The enemy now surely expects us to switch to the Outer River (Yangtze mainstream). We'll do the opposite—attack again from the Inner River. This will force them to deploy heavy defenses at Fucheng against the Inner River route." Thus Liu Yu devised his plan: the main force would advance via the Outer River straight to Chengdu, while sending decoy troops to feign an Inner River attack. To maintain secrecy, he sealed the complete battle plan with orders that Zhu Lingshi could only open it upon reaching Baidicheng. As predicted, Qiao Zong took the bait, concentrating defenses along the Inner River, whereupon Zhu Lingshi defeated him.

Later military theorists expanded on this:

Chen Hao pointed out that Du Yu's commentary only mentioned knowing the battlefield but neglected the timing. Without knowing the exact battle date, one couldn't make precise plans like Xiang Yu's famous pledge to Cao Jiu: "Within fifteen days I'll surely pacify Liang territory."

Mengshi argued that one must first survey the terrain's vulnerabilities, determine the battle date, then march a thousand li to meet it. If the enemy arrives first, one can then "await the fatigued with repose."

Du You synthesized these views: "A skilled commander must know both time and place of engagement, arranging marches accordingly—distant troops depart first, nearby ones later—all converging punctually like marketgoers. The crux is preventing the enemy from learning the specifics, thus forcing them to scatter defenses."

Mei Yaochen and Wang Zhe both emphasized that accurate prediction of battlefield and timing enables thousand-li marches to meet the appointed hour. Wang Zhe particularly noted one must first understand terrain and enemy disposition, then calculate distances and vulnerabilities through military science to determine the opportune moment.

Through concrete historical examples and military commentary, this passage illustrates the crucial importance of spatiotemporal prediction in "knowing yourself and knowing your enemy," showcasing ancient strategists' sophisticated understanding of controlling war's temporal and spatial dimensions.

Victory in battle depends on selecting the right terrain and timing to defeat the enemy. Cao Cao (the Three Kingdoms strategist) explains that by observing and assessing the enemy's weak points and choosing the optimal day to engage, one masters this principle. Zhang Yu (Song dynasty commentator) adds that before launching an attack, commanders must thoroughly understand the battlefield conditions. When troops arrive, they should compel the enemy to fight at the time of our choosing. Knowing where and when to engage allows concentrated forces to prepare fully—even armies a thousand miles apart can coordinate effectively.

For example, during the Spring and Autumn period, Jian Shu foresaw that Jin forces would ambush at Mount Xiao—a classic case of knowing the battleground. In the Western Han, Chen Tang predicted the Wusun army would retreat after five days of siege, demonstrating foresight of timing. Similarly, during the Warring States era, Sun Bin laid an ambush at Malingdao, calculating Pang Juan's troops would arrive at dusk—another illustration of this principle.

Without knowledge of the battlefield and timing, forces become disjointed: the left flank cannot aid the right, vanguards cannot protect rearguards, let alone units separated by dozens of miles. Du Mu quotes Guanzi: "To march without settled plans is to court destruction." Du You adds that if the enemy seizes advantageous terrain first, hastily deployed troops will descend into chaos, with even nearby units failing to support each other across ten-mile gaps. Mei Yaochen notes, "If close quarters offer no relief, how much less distant ones?" Zhang Yu elaborates: ignorance of the enemy's approach route and timing leads to inadequate preparation; sudden encounters with strong foes force reckless engagements where even neighboring units cannot assist, much less distant ones.

In my view, the Yue army's numerical superiority proved meaningless for victory. Cao Cao observes that while Yue forces massed together, they lacked organization. Li Quan argues the Yue failed to select terrain and timing—without these, numbers alone cannot secure triumph. Chen Hao points out this was Sun Wu's analysis for King Helü of Wu; the historical Wu-Ye enmity made Yue the natural example. Both Jia Lin and Mei Yaochen stress that without knowledge of battlefield and timing, troop numbers cannot determine victory. Mei Yaochen clarifies: Wu and Yue were rival states—here, Yue symbolizes any army ignorant of military strategy.

This passage discusses the tactical concept of "using few to oppose many" in military strategy. Several strategists explain different approaches to confronting numerically superior enemy forces.

Wang Xi emphasizes the crucial factors of timing and situational assessment. Even if the Yue army possesses numerical superiority, their advantage becomes meaningless if they cannot coordinate reinforcements. Zhang Yu suggests the character "wu" (吾) here might be a scribal error for "Wu" (吴), given the frequent conflicts between the neighboring states of Wu and Yue. He explains that while the Yue forces may outnumber us, we can neutralize their advantage by denying them favorable battle terrain and opportunities, thereby dispersing their troops - hence the saying "victory can be crafted."

Du Mu stresses that victory lies in controlling the strategic initiative. Mengshi supplements this by noting that keeping the enemy uncertain about the time and place of engagement ensures our advantage. Mei Yaochen and Wang Xi both concur with this perspective. Zhang Yu further elaborates that while the chapter "Xing Pian" originally states "victory can be foreseen but not demanded," the phrase "can be crafted" here specifically refers to the Yue situation, as we can confidently predict they'll fail to secure advantageous terrain.

Regarding the principle that "numerous enemies cannot deploy their strength effectively": Du Mu proposes four strategic dimensions that can render even massive enemy forces incapable of engaging us. Mengshi advocates using stratagems to disperse enemy concentrations. Jia Lin recommends keeping the enemy preoccupied with self-defense. Mei Yaochen observes that when few can defeat many, numerical superiority becomes irrelevant. Zhang Yu synthesizes these views, concluding that by fragmenting enemy coordination, we nullify their numerical advantage.

The final discussion concerns "anticipating outcomes through strategic planning": Li Quan mentions using esoteric military calculations like Taiyi Dunjia to forecast battles. Mengshi states that by gauging enemy intentions and observing their movements, we can predict developments. Jia Lin emphasizes the importance of staff planning within the command tent to precalculate gains and losses. These perspectives collectively demonstrate how meticulous planning enables anticipation of war's decisive factors.

By observing the enemy's situation and analyzing their strategies and tactics, one can foresee the outcome of battle. Mei Yaochen remarked that through careful calculation, we can discern the strengths and weaknesses in the enemy's plans. Wang Xi noted that by studying the enemy's disposition, we can evaluate the quality of their strategies. Zhang Yu cited the historical example of Lord Xue (a strategist of the Western Han dynasty) who accurately predicted the three possible strategies Ying Bu would employ.

Through proactive probing, one can grasp the enemy's patterns of movement. Li Quan maintained that by observing celestial phenomena (such as cloud formations), the flight patterns of birds, and human behavior, one could deduce enemy movements. He gave examples: when Wang Xun attacked Kunyang during Wang Mang's reign, ominous mountain-like clouds pressed down on the camp, foretelling defeat; when cloud formations resembling dams appeared over General Wang Sengbian's camp, Hou Jing correctly predicted victory. Here, "auspicious birds" symbolize various omens. Li Quan interpreted "作" (zuò) as "reconnaissance."

Du Mu explained "作" as provocation—deliberately stimulating the enemy to elicit revealing responses. He recounted a Warring States anecdote: when Marquis Wu of Wei asked how to assess an enemy commander's capability, Wu Qi advised sending a small detachment to provoke them. If the enemy maintained disciplined formations during advance and retreat, avoided reckless pursuit, and resisted bait, their commander was competent; but if they chased chaotically or greedily pursued advantages, they could be decisively engaged.

Chen Hao viewed "作" as active manipulation—creating scenarios of gain and loss to force enemy reactions, thereby exposing their operational patterns. Jia Lin emphasized that skilled scouts must thoroughly understand the enemy's behavioral rhythms. Du You pointed out that by monitoring the enemy's emotional fluctuations (anger or joy) and concrete actions, one could anticipate tactical shifts and predict outcomes. Mei Yaochen added that enemy patterns often reveal themselves under our provocations. Wang Xi stressed the importance of timing in such maneuvers. Zhang Yu provided examples: Duke Wen of Jin provoked Zi Yu by detaining Chu envoys, prompting his reckless advance; Zhuge Liang humiliated Sima Yi by sending women's attire, yet Sima Yi maintained his defensive posture—both cases demonstrating how "showing form" (形之) exposes enemy vulnerabilities.

The passage concludes with "by displaying forms, one discerns the grounds of life and death"—meaning feigned movements reveal critical terrain, just as a Go player identifies "eyes" (vital points) on the board. In warfare, identifying these decisive positions determines victory or defeat.

Li Quan explains that when breaking enemy formations and devising ingenious strategies on the battlefield, one must sometimes deliberately conceal banners and silence war drums to feign weakness; other times, one should set up illusory campfires and flags to simulate formidable strength. Placing soldiers in mortal danger can ignite their will to survive, while stationing them in comfortable circumstances may erode their fighting spirit. Thus, life and death often hinge upon the terrain conditions. Han Xin’s strategy at the Battle of Jingxing and Liu Yu’s northern expedition crossing Mount Daxian both exemplify this principle.

Du Mu interprets "the grounds of life and death" as referring to battlefield terrain. Positioning troops in perilous situations can galvanize their combat effectiveness, whereas placing them in secure areas may breed complacency. By employing various methods to confuse the enemy and observing their reactions, one can adapt flexibly to their movements, thereby mastering the pivotal factors of life and death on the battlefield.

Chen Hao adds that as long as the enemy makes a move, their strengths and weaknesses become discernible. A strategist skilled in the art of war always seizes advantageous terrain, while the inept often entrap themselves in danger. Meng Shi points out that by assessing the relative positions of both sides and the terrain they occupy, one can determine where lies the path to life and where the road to death. Jia Lin believes that analyzing the enemy’s formation alone can foretell their points of vulnerability. Mei Yaochen and He Shi both align with Du Mu’s perspective.

Zhang Yu synthesizes these views: when feigning weakness, the enemy will advance recklessly; when projecting strength, they will retreat cautiously. By observing the enemy’s responses to these maneuvers, one can gauge the favorability of their terrain. As mentioned earlier, "a commander skilled in manipulating the enemy can make them obey through deception"—this encapsulates the idea. The so-called "grounds of death" refer to terrain prone to annihilation, while "grounds of life" denote terrain conducive to combat. Through probing engagements, the relative strengths and weaknesses of both sides become apparent.

Cao Cao interprets "probing" (角, jiao) as a form of assessment. Li Quan elaborates that by comparing the strength and morale of both armies, one discerns their true conditions. Du Mu cites the Guanzi: "Those skilled in attack first evaluate their own forces before striking the enemy; they consider their own provisions before cutting off the enemy’s supplies." When Sima Yi campaigned against Liaodong, his subordinate Chen Gui questioned why they didn’t attack swiftly, as they had done against Shangyong. Sima Yi replied: "Meng Da has fewer troops but a year’s worth of provisions; we outnumber him four to one but have only a month’s rations. We must resolve a year’s worth of warfare within a month." This perfectly illustrates the military axiom of "probing the enemy’s substance and void."

This military strategy discusses how to formulate battle tactics by observing an enemy's strengths and weaknesses. The core principle states: When the enemy has superior numbers but lacks provisions, while our forces are fewer but well-supplied, we should deliberately appear weak to lull them into complacency. Then, when weather conditions improve, launch relentless day-and-night attacks to secure victory (Emperor Taizong of Tang historically employed this method to pacify Liaodong).

Annotations by military strategists elaborate:

Mei Yaochen points out that one must compare (measure) the disparity between enemy and friendly forces to identify their strengths and vulnerabilities. Wang Xi explains that "measure" refers to mutual assessment—only by discerning the enemy's true condition can one devise effective offensive or defensive strategies. Zhang Yu adds that understanding the enemy's strong points (surplus) and weak points (deficiency) is key to victory, noting that Emperor Taizong also emphasized deploying one's own strengths against the enemy's weaknesses in battle formations.

The highest level of military command lies in making troop movements utterly unpredictable (formless). Li Quan states that in such a state, even if the enemy sends deep-cover spies (penetrating reconnaissance), they cannot uncover the true situation; even the wisest strategists are left helpless. Du Mu further explains that once this level is achieved, the army may appear to have formations (visible ranks), but its tactical shifts remain unfathomable (hidden adaptability). He Shi calls this "knowing the subtle" (zhi wei)—the ability to perceive minute changes, while Zhang Yu concludes that this art of warfare begins with feints and illusions, ultimately reaching a state where no trace can be followed.

Finally, Cao Cao and Li Quan clarify: True victory comes from adapting flexibly to enemy circumstances (adjusting tactics according to the situation), a level of sophistication ordinary minds cannot comprehend. Like a master chess player whose seemingly casual moves conceal profound calculations, outsiders see only the surface, oblivious to the underlying principles.

This passage reveals the profound mysteries of achieving victory in military operations. The true Dao (Way) of warfare lies in adapting flexibly to the enemy's changing circumstances, rather than relying on fixed tactics.

A skilled commander must observe the transformations in the enemy's formations (xing) to devise winning strategies - a wisdom beyond ordinary soldiers' comprehension. As Du Mu noted, only the wise can perceive battlefield dynamics, while common minds cannot fathom such subtleties. Mei Yaochen added that while everyone sees our army's victorious outcome, none understand it resulted from countermeasures taken in response to the enemy's shifting formations.

Cao Cao explained that true victory comes not from applying identical methods against all enemies. Li Quan observed that while victories become public knowledge, the specific methods remain profoundly concealed. Du Mu further clarified that people only witness our army making the enemy reveal signs of defeat, unaware these employ strategies from the Thirty-Six Stratagems like "appearing distant when near, or near when distant." Just as in Han Xin's last-stand battle at the river, Zhao troops only saw Han forces fighting desperately, ignorant this was deliberately designed tactics.

Thus, brilliant commanders never repeat identical victory methods, but respond with infinite variations according to enemy movements. Li Quan termed this "adapting changes as appropriate," while Du Mu called it "enemy changes, we change." As Du You stated, this requires commanders to possess the talent for improvisation (deadly officials). Jia Lin concluded that achieving victory by responding to enemy changes represents warfare's highest attainment.

These commentaries emphasize one core principle: true military wisdom resides not in fixed tactics, but in flexible adaptation to actual circumstances. This capacity for spontaneous response constitutes a commander's most precious quality.

The Dao (Way) of employing troops flows with endless transformations like water. Mei Yaochen states one should not rigidly adhere to fixed patterns, but respond flexibly according to circumstances. Wang Xi points out that while the fundamental principles of victory remain constant, the specific methods for defeating enemies are infinitely varied. He Shi further explains that previously successful tactics should not be mechanically repeated - one must adapt to emerging enemy situations with fresh countermeasures rather than copying old approaches.

The patterns of warfare mirror water's nature: Meng Shi illustrates how military dispositions flow like water, with no fixed tempo of swiftness or slowness. Just as water naturally avoids heights and seeks low ground (Mei Yaochen notes this as water's intrinsic quality), military strategy should avoid enemy strongholds and strike vulnerable points (Zhang Yu emphasizes this as the advantageous approach). Water shapes its course according to terrain (both Du Mu and Mei Yaochen stress following the land's contours), just as battle plans must adapt to enemy conditions for victory.

Li Quan elaborates: Without observing the enemy's disposition, victory cannot be achieved. Against lightly equipped troops employ rapid engagement; against heavily fortified positions devise methods to lure them out; against enraged forces provoke them further; against superior strength adopt delaying tactics. When facing arrogant commanders appear weak; against greedy generals use bait; with suspicious leaders employ deception. Du Mu, Jia Lin and others all emphasize striking where the enemy is vulnerable. Just as water follows the land's formations to create different currents, military operations must target the enemy's weak points to prevail.

Thus warfare has no constant disposition (Mei Yaochen advises adjusting according to enemy situations), just as water has no fixed shape (Meng Shi compares battlefield dynamics to ever-changing terrain). Those who can adapt flexibly to enemy transformations and achieve victory may be called divine in military command. Cao Cao concludes: Even the most powerful momentum eventually declines, and exposed formations inevitably fail - therefore one must respond to the enemy's changes to remain invincible.

The art of warfare, when capable of adapting to circumstances to achieve victory, resembles divine power. Li Quan states that those who master this art may be called "divine soldiers." Du Mu explains: The disposition of troops manifests according to the enemy's situation, with the initiative not in our hands—hence there is no fixed formation. Just as water's shape is determined by the terrain while having no constant form of its own, when flowing through lowlands it can even move massive boulders. Similarly, warfare attains miraculous efficacy when it responds to the enemy's changing conditions.

Mei Yaochen adds that such transformations are subtle and unfathomable. Wang Xi elaborates further: While warfare follows fundamental principles (such as avoiding the solid to strike the void), it has no fixed patterns and must adapt flexibly to the enemy—like water's inherent tendency to flow downward without a constant shape, conforming to the land's contours. Even troops in disadvantageous positions can reverse defeat through mastery of transformation, let alone elite forces. He Shi observes that tactical adaptability relies on strategic wisdom; when such wisdom reaches unfathomable depths, it attains divine marvel. Zhang Yu concludes that after grasping the basic battle situation, achieving flexible victory through responsive adaptation reaches a refinement bordering on the supernatural.

Just as the Five Phases (Wood, Fire, Earth, Metal, Water) cycle through mutual conquest without permanent dominance (Du You notes their rotating ascendancy; Wang Xi emphasizes their mutual restraint), and the four seasons alternate without fixed transitions (Du You describes their cyclical succession; Wang Xi their interchanging rhythms), daylight waxes and wanes while the moon progresses through phases of birth and death (Cao Cao remarks that warfare, having no fixed model, must adjust like the moon's phases). Li Quan draws parallels with natural phenomena: The Five Phases have periods of flourishing and decline; seasonal cold and heat shift unpredictably; in celestial motion, the spring and autumn equinoxes balance day and night, the summer solstice brings prolonged daylight while winter reverses this, and the moon cycles from new moon to first quarter, full moon, last quarter, and darkness. Sunzi thus illustrates that since natural laws themselves are mutable, military strategy cannot possibly remain rigid. Mei Yaochen interprets these as metaphors for battlefield adaptability, while Wang Xi stresses they demonstrate warfare's rejection of fixed templates.

(Notes: 1. Retains terms like "Five Phases" and "lunar phases" with contextual explanations; 2. Integrates commentaries organically; 3. Preserves original imagery through similes like "just as"; 4. Adds explanatory details such as moon phase transitions; 5. Structures logical progression through paragraphing)

Zhang Yu (the commentator) explains that the waxing and waning of the Five Phases (Wood, Fire, Earth, Metal, Water), the cyclical alternation of the four seasons, and the phases of the moon's waxing and waning—all these resemble the shifting circumstances of warfare in having no fixed patterns. Just as the operations of nature follow no constant way, so too must military strategy adapt flexibly to actual conditions rather than clinging to rigid formulas.