The old saying goes, "He who strikes first has the advantage; he who strikes later suffers the consequences." In military affairs, "seizing the initiative" is also an important principle. As early as in the "Zuo Zhuan," there is the expression "the first to act seizes the opponent's will." Later generations also often emphasized "speed is essential in war" and "I would rather attack others than be attacked," all meaning to strive for the advantage of striking first in battle. However, things are not absolute. Under certain conditions, "responding after the enemy" is also an important tactic in military struggle, and it exists in a dialectical unity with "seizing the initiative." Its essence is active defense—using defense as a means and counterattack as the goal, an offensive defense. It often becomes an important tool for the weaker side to overcome the enemy. The Battle of Chengpu between the states of Jin and Chu during the Spring and Autumn period is one of the classic historical examples of this.
The Battle of Chengpu took place in the 28th year of Duke Xi of Lu (632 BC). It was the first strategic showdown between the states of Jin and Chu during the Spring and Autumn period, fought to determine dominance over the Central Plains. In this war, the Chu army held an advantage in strength, but due to the Jin army's skill in "strategic maneuvering" and "diplomatic warfare," and their adoption of a correct strategy of exploiting strengths while avoiding weaknesses and "responding after the enemy" in campaign guidance, they ultimately defeated the seemingly invincible Chu army, "establishing their prestige and securing their hegemony," and dominating the Central Plains.
During the Spring and Autumn period, major states competed for supremacy, with the state of Qi in the east rising first. After Duke Huan of Qi died, Qi experienced continuous internal turmoil, and its hegemony declined. At this time, the state of Chu, located in the middle reaches of the Yangtze River, took the opportunity to expand its influence northward into the Yellow River basin. In the Battle of Hongshui, Chu defeated Duke Xiang of Song's attempt to establish hegemony, extending its sphere of influence between the Yangtze, Huai, Yellow, and Han rivers, and bringing numerous smaller states such as Zheng, Cai, Wei, Song, and Lu under its control. Just as Chu's power was rapidly expanding northward, the state of Jin, located in present-day Shanxi, northern Henan, and southwestern Hebei, also began to flourish. In 636 BC, after years of exile, the Jin prince Chong'er overcame great hardships and finally returned to his state to ascend the throne, becoming Duke Wen of Jin. After taking power, he reformed domestic politics, appointed the worthy and capable, developed the economy, advocated frugality, and strengthened the military; externally, he raised the banner of "Respecting the King," seeking alliances, thus gradually building up the powerful strength needed to contend for hegemony over the Central Plains.
The rise and growth of Jin caused serious unease in Chu. The contradictions between the two states consequently became increasingly sharp. The struggle for control over the state of Song ultimately led to the full-scale escalation of this conflict.
In 634 BC, the state of Lu, having allied with the states of Cao and Wei, was repeatedly attacked by Qi and thus requested aid from Chu. Meanwhile, Song, which had been forced to submit to Chu after the Battle of Hongshui, seeing the growing strength of Jin under Duke Wen, shifted its allegiance to Jin. To maintain its dominant position in the Central Plains, Chu launched military campaigns against Qi and Song, aiming to curb Jin's eastward and southward expansion. Unwilling to remain confined north of the Yellow River for long, Jin seized this opportunity to send troops into the Central Plains under the pretext of rescuing Song.
In the winter of 633 BC, King Cheng of Chu led a multi-state coalition army of Chu, Zheng, Chen, and Cai to attack Song, besieging its capital Shangqiu. In the midst of this crisis, Duke Cheng of Song sent his Grand Marshal Gongsun Gu to Jin to plead for help. The Jin minister Xian Zhen believed this was the perfect opportunity to "repay kindness, relieve suffering, establish prestige, and secure hegemony," and strongly advocated that Duke Wen of Jin send troops. However, at that time, the states of Cao and Wei lay between Jin and Song, making a long-distance expedition risky with the danger of enemy attacks on the flanks; moreover, the Chu army was powerful, and a direct confrontation offered no guarantee of victory. As Duke Wen of Jin hesitated over this decision, Hu Yan further proposed to him: first attack the states of Cao and Wei to draw the Chu army northward, thereby relieving the siege of Song. This solidified Duke Wen's resolve to send troops. After the strategic plan was set, the Jin ruler and his ministers immediately made pre-war preparations, expanding their original two armies into three—Upper, Middle, and Lower—and appointing a batch of relatively outstanding noble officials as commanders of each army. Once preparations were complete, in January 632 BC, Duke Wen of Jin led his large army across the Yellow River to attack Wei, quickly occupying the entire territory of Wei. Then, the Jin army launched an attack on Cao, capturing its capital Taoqiu (present-day Dingtao, Shandong) in March and capturing Duke Gong of Cao, the ruler of Cao.
The original intention of the Jin army's attack on Cao and Wei was to lure the Chu army northward, but the Chu army remained unmoved, continuing to focus its full strength on besieging Shangqiu, the capital of Song. Consequently, Song sent Men Yin Ban to Jin again to urgently request reinforcements. This placed Duke Wen of Jin in a difficult position: if he did not send reinforcements, Song would not be able to hold out and would certainly surrender to Chu and cut ties with Jin, damaging his plan to establish hegemony over the Central Plains; but if he sent reinforcements, the original strategic plan to lure the Chu army into a decisive battle in the territories of Cao and Wei would fail, and with limited forces, fighting the Chu army far from home would likely be difficult to win. Therefore, Duke Wen of Jin once again convened his ministers to discuss the matter. Xian Zhen carefully analyzed the situation and suggested that Song should publicly appear to distance itself from Jin, then send a generous gift through Song to the states of Qi and Qin, asking them to request the Chu army to withdraw. At the same time, Jin would gift part of the land of Cao and Wei to Song to strengthen Song's resolve to resist Chu. Chu had originally been allied with Cao and Wei; now, seeing their lands occupied by Song, they would certainly refuse the mediation of Qi and Qin. Qi and Qin, having accepted Song's generous gifts, would then resent Chu for ignoring their mediation and thus align with Jin, sending troops to fight against Chu. Duke Wen of Jin highly praised this plan and immediately implemented it. King Cheng of Chu indeed rejected the mediation of Qi and Qin, and seeing that Chu did not give them face, Qi and Qin became greatly angered and sent troops to assist Jin. Qi and Qin were both major powers at the time; their abandonment of a neutral stance significantly altered the balance of power between Jin and Chu.
King Cheng of Chu saw that the three major powers of Jin, Qi, and Qin had formed an alliance, and the situation was clearly unfavorable to him. He proactively withdrew the Chu army to Shen (present-day Nanyang, Henan) and ordered Shen Shu, the official garrisoning Guyi, to quickly evacuate Qi, demanding that Prime Minister Zi Yu withdraw the main Chu forces from Song to avoid conflict with the Jin army. He warned Zi Yu that Duke Wen of Jin was no ordinary person and should not be underestimated; matters should be handled according to ability, knowing when to stop and when to retreat. However, Zi Yu was arrogant and self-assured, completely ignoring King Cheng's advice. He insisted that King Cheng allow him to fight a decisive battle against the Jin army to dispel rumors of his incompetent command and requested additional troops. King Cheng was indecisive; he agreed to Zi Yu's request for a decisive battle, hoping he might win by luck, but was unwilling to provide Zi Yu with sufficient forces for a decisive battle, sending only a small number of reinforcements—the Western Guang, the Eastern Palace, and the Six Clans of Ruo'ao.
After receiving this part of the reinforcements sent by King Cheng, Zi Yu became even more determined to fight the Jin army. To find a pretext for a decisive battle, he sent an envoy, Wan Chun, to deliberately present Jin with a "ceasefire" condition: Jin would withdraw from Cao and Wei, allowing Cao and Wei to be restored, and in return, the Chu army would lift the siege on the capital of Song and withdraw from Song. Zi Yu's move was ill-intentioned, actually aiming to make Jin abandon its efforts to dominate the Central Plains and command the feudal lords. However, Duke Wen of Jin was a step ahead, adopting the even more sophisticated strategy proposed by Xian Zhen: on one hand, he pretended to accept the offer, secretly agreeing to restore Cao and Wei on the condition that they sever ties with Chu. On the other hand, he detained the Chu envoy Wan Chun to provoke Zi Yu into seeking battle. Seeing his envoy detained and Cao and Wei defecting to Jin, Zi Yu was indeed enraged. Relying on the numerical superiority of the Chu-Chen-Cai coalition forces, he aggressively charged toward the Jin army, seeking a strategic showdown. Duke Wen of Jin, seeing the Chu army advancing toward the Cao capital Taoqiu, ordered his troops to actively "retreat three stages" to the predetermined battlefield—Chengpu (present-day Pucheng, Henan)—to avoid the sharp edge of the Chu army, choose a favorable moment for battle, lure the enemy deep, and "respond after the enemy."
The Jin army's "retreat three stages" was actually a brilliant strategic move by Duke Wen of Jin to outmaneuver the enemy. Politically, it seized the initiative—"the ruler retreats while the minister attacks, the fault lies with the latter"—winning public sympathy. Militarily, it created advantages—facilitating the rendezvous and concentration of forces with allied armies from Qi and Qin; boosting the morale of Jin soldiers; securing the battlefield first to await the enemy in rest, and so on. Thus, it laid a solid foundation for the Jin army's strategy of "responding after the enemy" to win the decisive battle. Many in the Chu army found the Jin army's active retreat suspicious and advocated caution, halting the pursuit. However, the headstrong and self-willed Zi Yu believed this was the perfect opportunity to annihilate the Jin army and reclaim Cao and Wei, and ordered his troops to pursue all the way to Chengpu.
The Jin army took position at Chengpu, and the armies of Qi, Qin, Song, and other states gradually arrived and joined them. Duke Wen of Jin inspected his forces, believing their morale was high and preparations were adequate, ready to engage the Chu army. On the Chu side, preparations for the decisive battle were also actively underway. Zi Yu divided the Chu army and the forces of Chen and Cai into three armies: the Center, Left, and Right. The Center Army was the main force, directly commanded by himself; the Right Wing Army, composed of the armies of Chen and Cai with weak combat effectiveness, was led by the Chu general Zi Shang; the Left Wing Army, also Chu troops, was commanded by Zi Xi.
On April 4, 632 BC, the sky over the Chengpu area was filled with the clouds of war as the armies of Jin and Chu engaged in a massive chariot battle. In the decisive battle, the Jin army, targeting the Chu deployment with a strong center and weak flanks, and exploiting the weaknesses of Chu commander Zi Yu's arrogance, underestimation of the enemy, and lack of understanding of the real situation, adopted a combat strategy of first attacking the flanks and then assaulting the center, launching a focused offensive. The Deputy Commander of the Lower Army of Jin, Xu Chen, covered the horses pulling the chariots with tiger skins and unexpectedly launched a fierce attack first on the weakest part of the Chu army—the Right Wing Army composed of Chen and Cai forces. The Chen and Cai troops, caught off guard by this sudden and strange assault, were immediately thrown into panic and routed at first contact. Thus, the Chu Right Wing was quickly annihilated.
Next, the Jin army employed the tactic of "displaying formations to move the enemy," luring the enemy to attack and then dividing and annihilating them, against the Chu Left Wing Army. Hu Mao, the Commander of the Upper Army of Jin, deliberately raised two large flags on his chariot and retreated, feigning a withdrawal. At the same time, Luan Zhi, the Commander of the Lower Army of Jin, also dragged branches behind chariots at the rear of the formation, raising dust from the ground, pretending that the Jin forces behind were also retreating, to lure the Chu army into attacking. Zi Yu, unaware of the ruse, ordered the Left Wing Army to pursue. Xian Zhen, the Commander of the Middle Army of Jin, and his Deputy Chi Zhen, seeing that the Chu army had fallen into the trap and was blindly attacking, immediately commanded the elite Middle Army to strike sideways against the Chu Left Wing. Hu Mao, the Commander of the Upper Army, and his Deputy Hu Yan also took the opportunity to turn back and launch a pincer attack. The Chu Left Wing, hit by this assault, had its retreat cut off, was completely surrounded, and was soon destroyed. At this point, Zi Yu, seeing that both his left and right wings had been defeated and the situation was hopeless, had no choice but to order the Center Army to quickly disengage from the battlefield, barely preserving the core force. After the defeat, the Chu army retreated southwest to Lian Gu, and Zi Yu was soon forced to commit suicide. Thus, the Battle of Chengpu ended with the Jin army achieving a decisive victory. The troops lost their formation, and thousands of men ran around like headless flies.
Standing on the hilltop, Zhang Er waved his command flag, ordering his soldiers to attack from both sides. The soldiers' courage doubled, rushing forward and bravely fighting the enemy, completely routing the disorganized Zhao army in one fell swoop. The general Chen Yu was hacked to death in the chaos. After the war, someone reported to Han Xin that they had captured a Zhao officer.
Han Xin was about to ask who it was when he saw several soldiers roughly pushing a blood-soaked man toward him. Upon questioning, he exclaimed—it was none other than Li Zuoche, the general of Zhao! He had long admired General Li's talent. Previously, he had issued an order: whoever captured Li Zuoche alive would be rewarded with a thousand catties of gold. He never expected his subordinate to actually capture him. Han Xin opened his arms and shouted, "General Li!" Li Zuoche, upon seeing Han Xin, turned his head away.
Han Xin immediately brought Li Zuoche under his tent, used his sword to cut the ropes binding him, and then bowed deeply. Li Zuoche couldn't help but recall the rumor about Han Xin crawling between someone's legs as a child, spat in disgust, and said, "Stop your tricks! If you want to behead me, just do it. I'm at your mercy!" Han Xin didn't say much, ordered someone to quickly prepare a banquet, and wanted to calm the nerves of General Li. At the banquet, Han Xin repeatedly toasted Li Zuoche and asked him for advice on defeating the enemy. Ji Zuoche spread his hands and said, "Now that I'm your prisoner, how can I discuss strategies with you?" Han Xin smiled and said, "It is said, 'When three walk together, there is always a teacher among them.' In warfare, I am inferior to you..." Li Zuoche was startled: "How so?" Han Xin said, "Back then, if King Zhao had truly adopted your advice, my head would probably have been gone long ago!" This sentence made Li Zuoche blush and stammer, "General Han, you flatter me, you flatter me!" Han Xin's sincere attitude deeply moved Li Zuoche. When Han Xin repeatedly asked him for advice on what to do next, Li Zuoche said, "In my opinion, your army, after prolonged warfare, is already exhausted and unable to fight again!" Han Xin countered, "So you're saying it won't be easy for me to continue attacking Yan?" Li Zuoche nodded. Han Xin pressed further, and Li Zuoche said, "Let me think about it some more." Early the next morning, as Li Zuoche just opened his eyes, he saw Han Xin standing by his bed, waiting for his advice. Li Zuoche hurriedly stood up and whispered, "I think you should lay down your arms and rest!" "Lay down your arms and rest!" "Yes, station your troops on the border of Yan. Yan won't know what you're up to, but in reality, you're recuperating and building strength. Then, just send an envoy to Yan with a letter, telling the King of Yan when you plan to attack them. Yan will certainly tremble with fear and submit to you. In this way, the neighboring state of Qi will also surrender to you!" Han Xin, upon hearing this, was overjoyed, clapping his hands three times: "General Li, are you perhaps a celestial star descending to earth!" He truly adopted Li Zuoche's advice and conquered Yan without expending much effort. At the victory celebration, Zhang Er, puzzled, asked Han Xin, "Military texts say that troop deployment should be near mountains and rivers, but you set up your formation with your back to the water. At the time, the soldiers were all不服 (unconvinced), yet you still won. I don't understand the reasoning behind this." Han Xin replied, "Military texts also say, 'Place them in a desperate situation and they will survive; place them in a doomed situation and they will live.' You know, most of our troops are newly recruited soldiers, lacking strict training and strong fighting spirit. Besides, I haven't led this army for long and haven't established real authority. In a crisis, the men won't listen to my commands. Therefore, I placed the troops in a perilous situation, forcing them to fight individually for survival. If we had camped in a safe place with an escape route behind, as soon as they saw the enemy charging fiercely, they would definitely flee in a panic. How could we fight then?" This explanation convinced everyone completely.
The soldiers then started asking in a chorus why Yan had surrendered so easily. Han Xin smiled slightly and pushed Li Zuoche forward, saying, "You have to ask him. He is my teacher; I acted only after listening to what my teacher said." Li Zuoche, embarrassed, waved his hand, "Where, where. I'm just your prisoner; how can I be a teacher?" Han Xin declared loudly, "He is my teacher, and also the teacher of all the generals!" When he explained the whole story, the soldiers present were so astonished that their mouths hung open, unable to speak for a long time.