In the Chapter of Initial Estimations(Laying Plans) of The Art of War, Sun Tzu laid out twelve deceptive stratagems of warfare, the eleventh of which reads: “Wear out the rested troops.”(佚而勞之)
The Chinese character “yi” means well-rested and comfortable, while “lao” signifies toil and exhaustion. The straightforward essence of this stratagem is clear: when the enemy army is fully manned, well-rested, stable in morale and holds the advantage of ample recuperation, we must avoid reckless head-on assaults. Instead, we should launch repeated harassment and constant maneuvers to wear down their physical strength, troop morale and war preparations. This will leave the once comfortable enemy marching day and night in utter fatigue, stripping them of all combat advantages.
Many people mistakenly believe that strategies to exhaust the enemy are passive defensive measures adopted only to stall for time, yet the truth is exactly the opposite. A close reading of the core thought of military tactics reveals that “wear out the rested troops” is never a passive avoidance of battle; it is an offensive strategy that takes full initiative to control the rhythm of combat. The heart of warfare never lies in clashing head-on to compare troop strength, but in maneuvering the enemy, disrupting their deployments, and reversing the balance of power between the two sides at minimal cost.
During the late Spring and Autumn Period‘s struggle for hegemony between Wu and Chu, Wu Zixu, a distinguished minister of Wu, put forward a three-pronged plan to exhaust Chu. This plan stands as an unparalleled practical model of this stratagem, fully recorded in Zuo’s Commentary on the Spring and Autumn Annals, 30th Year of Duke Zhao, offering invaluable military reference for generals of later generations.
It is worth pointing out that Sun Wu(Sun Tzu), the author of The Art of War, was the chief architect of this largest military campaign Wu had ever launched since its founding. King Helü of Wu appointed Sun Wu as the commanding general, with Wu Zixu and Bo Pi serving as his deputy generals, granting Sun Wu supreme battlefield command authority.
In the late Spring and Autumn Period, Chu dominated the south with vast territory and formidable troops, ranking as the most powerful state in the southern region. Meanwhile, Wu rose steadily in strength. King Helü of Wu harbored lofty ambitions, determined to conquer mighty Chu and seize hegemony over the Central Plains. In 512 BCE, after all preparations were complete, Helü summoned his strategist Wu Zixu to consult on the campaign against Chu:
“Long ago you devised a plan of vengeance and laid out a grand scheme to destroy Chu. Now the time has come – how shall we launch our full-scale invasion?”
Faced with his ruler’s eagerness for a decisive single battle, Wu Zixu did not agree to hasty combat. Instead, he pinpointed a fatal internal flaw within Chu’s governance, stating sharply:
“Chu has numerous conflicting ministers, with no single person empowered to bear the burden of crisis.”
Wu Zixu claimed that the Chu court was filled with powerful officials divided into rival factions whose contradictory opinions hindered one another. No leader could make independent decisions in times of trouble, and military and civil decrees lacked unity. Though Chu appeared prosperous, its internal governance was riddled with vulnerabilities. From Wu Zixu’s perspective, despite Chu’s massive army, internal court strife made its forces vulnerable to exhaustion through external manipulation – the perfect opening to deploy the tactic of wearing out rested troops.
Drawing on this critical weakness of Chu, Wu Zixu presented his enduringly famous plan to exhaust Chu. He urged the king to abandon the pursuit of a quick decisive victory and refrain from concentrating all Wu troops for a head-on clash with Chu’s main force. Instead, the elite soldiers of Wu would be split into three mobile raiding detachments to launch rotating incursions along Chu’s borderlands. He outlined a complete tactical cycle: whenever one Wu division marched into Chu territory, panic would sweep the Chu court. Faced with border threats, Chu would mobilize its entire national army to march forth and engage. By the time Chu’s troops traveled thousands of li to reach the border, the Wu detachment would immediately retreat home for rest. The Chu soldiers would trudge back worn out, having chased an empty target. Yet no sooner had Chu’s army withdrawn to recuperate and regain comfort than a second Wu detachment would strike another section of Chu’s frontier.
This cycle repeated endlessly, forming a fixed tactical rhythm: When the enemy marches out, we retreat; when the enemy retreats to rest, we strike. If the enemy mobilizes its full army, our forces fall back to avoid combat; once the enemy disbands its troops to recuperate, we resume harassment. Wu Zixu summarized the core essence of this tactic in two concise military maxims:
“Harass frequently to exhaust them; deploy varied feints to mislead them.”
Constant simulated attacks drained the enemy’s stamina and morale, while ever-shifting lines of advance confused their judgment, leaving them unable to discern Wu’s true battle intentions.
This scheme fully embodied every layer of Sun Tzu’s maxim “wear out the rested troops”. Wu’s divisions rotated between combat and rest, sustaining abundant, well-rested combat power and holding absolute initiative over the battlefield. In contrast, Chu’s troops faced repeated emergency mobilizations and long marches, shuttling ceaselessly between border zones without day or night of reprieve. Military supplies were steadily depleted, morale gradually crumbled, and Chu’s once well-nurtured elite army sank into crippling fatigue wrought by unending maneuvers.
King Helü of Wu, well-versed in military wisdom, fully adopted Wu Zixu’s exhaustion strategy. Year after year of rotating border raids steadily drained Chu’s national wealth and military strength until the state fell into severe decline. Zuo’s Commentary preserved a precise account of this shift in strategic balance:
“From this time onward, Chu began to suffer ruinous strain.”
Chu’s vitality was sapped; its officials and commoners alike labored under constant marching, stripped of the capacity to mount steady resistance against Wu. The once unrivaled southern hegemon slid into irreversible strategic passivity.
Throughout this prolonged strategic contest, Wu never launched a large-scale head-on decisive battle, yet it subdued Chu without bloodshed. By skillfully applying military theory, Wu Zixu reshaped the offensive-defensive dynamic between Wu and Chu merely through maneuvering and draining the enemy’s strength, without costly mass combat. After years of building momentum, Wu seized the perfect opportunity when Chu’s troops were thoroughly fatigued and its border defenses full of gaps. Uniting its full army for a general assault, Wu shattered Chu’s main force in the Battle of Bo Ju, advanced unimpeded deep into Chu territory, and captured Ying, Chu’s capital – an extraordinary feat of defeating a stronger foe and seizing the heart of an enemy state.
Reviewing this Spring and Autumn campaign allows us to grasp the profound ingenuity of deceptive stratagems in The Art of War. The pinnacle of military command never lies in bloody frontal clashes to test relative strength, but in discerning the opponent’s vulnerabilities and seizing control of the battlefield tempo. When facing a well-rested, powerful enemy, one need not fear their sharp momentum; instead, create constant disturbances to maneuver them without cease, wearing out those at ease and throwing the stable into chaos.
Across China’s millennia of military history, Wu Zixu’s three-fold plan to exhaust Chu is far from unique. Many renowned generals of later dynasties adopted the core logic of “wear out the rested troops”, leaving three well-documented parallel classic battles recorded in official histories.
Case 1: Jin’s Three Divisions of Four Armies
The origin of the hegemonic rivalry between Jin and Chu can be traced back to the Battle of Chengpu in 632 BCE. This conflict marked the first large-scale head-on confrontation between the two states and served as a clear dividing line that completely reshuffled the power landscape of the Central Plains. Jin secured victory through ingenious strategic arrangements and brilliant command, yet Chu never sank into decline. Instead, frictions between the two sides intensified in the years that followed, officially kicking off the prolonged struggle for supremacy between Jin and Chu.
Long before Wu Zixu proposed his plan, Jin pioneered the tactic of rotating harassment to drain enemy strength, serving as the original inspiration for Wu’s scheme. At that time, Jin and Chu fought prolonged wars for supremacy. Chu’s army maintained long stretches of rest and robust combat capacity, making head-on Jin campaigns largely fruitless. Xun Ying, a minister of Jin, put forward the strategy of splitting Jin’s main army into three detachments to launch alternating southern raids on Chu’s borders.
Its tactical logic mirrored Wu’s later plan entirely: if one Jin detachment attacked, Chu would mobilize its full army to counter; as soon as Chu’s troops marched out, Jin’s raiders retreated; once Chu’s army returned to rest, Jin struck again. Nonstop back-and-forth maneuvers denied Chu’s troops consistent repose and drastically consumed the state’s grain reserves and resources. Zuo’s Commentary explicitly records that this tactic kept Chu’s army perpetually worn out, robbing the state of all initiative to march north for hegemony. Born a native of Chu, Wu Zixu drew on Jin’s mature exhaustion warfare, refined it to fit Wu-Chu geopolitics, and incorporated Chu’s internal court strife to craft his superior border harassment strategy.
Case 2: Peng Yue’s Raids Behind Enemy Lines
During the stalemate of the Chu-Han rivalry, Xiang Yu’s Chu army boasted crack troops and superior armor, forcing Liu Bang’s Han forces into repeated retreats on the main front. At this critical juncture, General Peng Yue opened a secondary theater behind Chu lines, perfectly embodying the wisdom of wearing out rested troops. Leading a swift mobile guerrilla force, Peng Yue avoided all head-on confrontations with Xiang Yu’s main army, instead launching repeated surprise strikes on Chu’s rear granaries, supply routes and garrison outposts.
Every time Xiang Yu marched with his elite troops to surround and suppress Peng Yue, Peng Yue immediately evaded battle and withdrew. As soon as Xiang Yu led his army back to the main front to fight Liu Bang, Peng Yue resumed sabotaging Chu’s supply lines. This endless tug-of-war forced Xiang Yu’s army to shuttle between two fronts without rest. His elite troops suffered sustained exhaustion, and grain shortages became frequent. Peng Yue’s unrelenting harassment pinned down Xiang Yu’s main force, laying the decisive groundwork for Liu Bang’s turnaround on the main battlefield and the eventual encirclement of Xiang Yu. It stands as a pivotal example of securing victory by exhausting the enemy in the Chu-Han wars.
Case 3: Wang Jian’s Static Ramparts to Wear Down Chu
In the late Warring States Period, Wang Jian, famed general of Qin, led 600,000 troops to invade Chu. Facing a fully mobilized, high-morale Chu army well-rested from prolonged garrison duty, Wang Jian refused to initiate combat rashly. Instead, he ordered his entire army to hold fast behind fortifications, devoting each day to troop rest, drills and physical recuperation. No matter how fiercely Chu’s soldiers taunted and challenged the Qin army, Wang Jian maintained his strict defensive posture.
Plagued by supply shortages, Chu troops repeatedly goaded Qin into battle. Yet denied the decisive fight they craved day after day, their fighting spirit steadily faded. The once vigorous, rested army grew weary and demoralized, forcing Chu’s generals to order a full retreat for rest. Seizing the moment when Chu’s troops were fatigued, lax and their battle formations disordered, Wang Jian launched a sudden full-scale assault, routing Chu’s main force completely and conquering the state of Chu. This campaign demonstrates the inverse application of the core logic behind “wear out the rested troops”: one can either actively raid to send strong enemies marching into exhaustion, or hold fast without combat to wear down the eagerness of foes desperate to fight. The central principle remains identical: disrupt the enemy’s opportunity to recuperate comfortably and seize the window for victory.
To wear out the rested enemy: drain their strength, confuse their hearts, mislead their stratagems, and sap their momentum. Wu Zixu’s plan to exhaust Chu, alongside the three other recorded campaigns, all achieved maximum strategic gains at minimal military cost. They validate the unchanging military truth laid down by Sun Tzu across two millennia, and reveal an eternal rule of all contests: true victory never comes from winning a single head-on battle, but from draining the opponent of all capacity to fight long before the decisive clash.
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