The Battle of Boju

The Battle of Boju was a famous battle in ancient Chinese military history. In 506 BC, King Helu of Wu, assisted by Wu Zixu and Sun Tzu, led an army of 30,000, along with the forces of Cai and Tang, in a long-distance raid. They launched a surprise attack on the Chu army at Boju, winning five consecutive victories. They conquered the Chu capital Ying, shocking the Central Plains and establishing Wu as a dominant power in the late Spring and Autumn period.

The Course of the War

Diagram of the Wu-Chu War

Cai's Plea for Help

In the autumn of 506 BC, Nang Wa, the Grand Marshal of Chu, led his troops to besiege Cai, a small state that had submitted to Wu. Cai, in dire straits, appealed to Wu for assistance.

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Zuo Zhuan, Duke Ding, Year 4: In summer, Cai destroyed Shen. In autumn, Chu, due to Shen's demise, besieged Cai.

King of Wu Attacks Chu

Wu dispatched troops to rescue Cai. Helu personally led the expedition, with Sun Wu and Wu Zixu serving as major generals, and Helu's younger brother Fu Gai as the vanguard. The entire national force of 30,000 troops, both land and naval, set sail on warships, traveling up the Huai River. Tang also joined forces with Wu and Cai. The combined armies of Wu, Cai, and Tang advanced toward the Chu capital.

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Zuo Zhuan, Duke Ding, Year 4: In winter, the marquis of Cai, the general of Wu, and the marquis of Tang attacked Chu.

Leaving the Boats and Landing

Under Sun Wu's command, the Wu army bypassed Chu's defenses, sailed along the Huai River to the northeast of Chu, abandoned their boats at Huai Rui, and dispatched elite troops as the vanguard in a swift advance towards Ying. The surprise appearance of the Wu army in the heart of Chu territory made "achieving victory through surprise" a classic military strategy.

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Zuo Zhuan, Duke Ding, Year 4: They abandoned their boats at Huai Rui and, from Yu Zhang, bordered the Han River with Chu.

Wu and Chu Confront Each Other

Wu and Chu faced each other across the Han River. Shen Yin Xu, Chu's Left Sima (a military officer), devised a battle plan: he would lead his troops to flank the Wu army, while Nang Wa would block them on the west bank of the Han River. The Wu army found itself in a perilous situation.

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Zuo Zhuan, Duke Ding, Year 4:The Left Sima Xu said to Zi Chang: "You should follow the Han River and engage them from upstream and downstream, while I will completely destroy their boats outside the city walls and block the Da Sui, Zhi Yuan, and Ming E passes. You can then cross the Han River and attack them, while I attack from the rear. We are sure to defeat them decisively." This plan was then executed.

Internal Conflict in the Chu Army

Nang Wa, the Chu Grand Marshal, heeded the misguided advice of his subordinates and engaged the Wu army across the river, suffering three consecutive defeats.

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Zuo Zhuan, Duke Ding, Year 4:Wu Cheng Hei said to Zi Chang: "Wu uses wood, while we use leather; this cannot last. It's better to fight quickly." Shi Huang said to Zi Chang: "The Chu people are malicious but fond of their Sima. If the Sima destroys the Wu boats on the Huai River and enters through the blocked city gates, then they alone can defeat Wu. You must fight quickly, or you will not escape." So he crossed the Han River and formed ranks, from Xiao Bie to Da Bie. After three battles, Zi Chang knew it was impossible and wanted to flee.

Arrival at Ying 

The Chu army suffered a crushing defeat at Boju, and Nang Wa fled to Zheng. The remnants retreated to Qingfa Shui (present-day Ji Shui, west of Anlu, Hubei) southwest of Boju. The Wu army pressed their advantage, capturing half of the Chu forces. In five more battles, they arrived at Ying.

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Zuo Zhuan, Duke Ding, Year 4:On the Gengwu day of the eleventh month, the two armies met at Boju…The Wu army decisively defeated them. Zi Chang fled to Zheng………The Wu army pursued the Chu army to Qingfa…"Halfway across, then we can attack." Following this advice, they defeated them again. The Chu were eating, and the Wu forces attacked them and they fled. The Wu forces pursued them while eating, and defeated them at Yongpo. After five battles, they arrived at Ying.

Chu's Defeat    

Shen Yin Xu, upon learning of the Chu army's defeat, retreated and engaged the Wu army. Although he achieved some small victories, he was repeatedly injured and ultimately unable to turn the tide. Finally, seeing that the situation was hopeless, Shen Yin Xu ordered his men to cut off his head and present it to the Chu king. With this, the Chu army completely collapsed.

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Zuo Zhuan, Duke Ding, Year 4:The Left Sima Xu returned to rest and then defeated the Wu army at Yongpo, suffering injuries. Initially, the Sima had served under King Helu, and he was ashamed of being captured. He said to his men: "Who can save my head?" Wu Ju Bei said: “"I have truly failed you, what can be done!"After three battles, all resulting in injuries, he said: "I am no longer of use." Ju Bei took his cloth garment, cut his own throat and wrapped his head in it, hid his body, and offered his head to save himself.

King Zhao Flees to Sui

On the twenty-seventh day of the eleventh month, King Zhao of Chu and his entourage escaped. On the twenty-eighth day of the eleventh month, the Wu army captured Ying. King Zhao fled to Sui, and the Wu army pursued them and negotiated with Sui. Sui refused to hand over King Zhao under the pretext of an unfavorable divination. The Wu army retreated. King Zhao then formed an alliance with Sui.

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Zuo Zhuan, Duke Ding, Year 4:On the Ji Mao day (the twenty-seventh day of the eleventh month), the King of Chu took his sister Ji Mi, and gave her to me to lead him out…fled to Sui. The Wu army followed him and said to the people of Sui: "Those who are descendants of Zhou in Hanchuan, Chu has truly exterminated them. Heaven has induced its heart, to bring punishment to Chu, and you have also exiled him. What crime has the Zhou court committed? If you will consider the recompense of the Zhou court, and extend it to us, to support the will of Heaven, that would be your kindness. The fields of Hanyang, you truly possess them." …The people of Sui consulted divination and it was unfavorable. Then they told Wu:"Following Sui, to open a small but close area near Chu, Chu truly maintains it, and there has been an oath for generations, until now it has not been changed. If we were to fight and abandon it, how could we serve the king? The trouble of your affairs does not rest on just one person. If we attack Chu completely, how could we dare not obey orders."The Wu people then retreated…The king…made an alliance with the people of Sui.

Epilogue

In 505 BC, taking advantage of the weakened state of Wu's army due to a large portion being engaged in Chu and the resulting emptiness in its rear, Yue launched a major attack on Wu. Simultaneously, Shen Bao Xu, a high-ranking official of Chu, arrived in Chu with reinforcements from Qin, and the Wu army was defeated by the combined forces of Qin and Chu. In July, Chu destroyed Tang. In September, Fu Gai returned to Wu, proclaimed himself king, led his troops into battle against Helu, was defeated, and fled to Chu, where he was later ennobled as Tangxi Shi.

Analysis of Important Cultural Relics

Prince Guang's Halberd of Wu

This artifact was unearthed from a tomb in the Wenfeng Pagoda Cemetery in Suizhou. It is a double-headed halberd with spikes, with a spear point at the end of the shaft. Two halberds are vertically placed on the upper part of the shaft; the upper halberd has an inner edge, while the lower one does not. Both halberds share identical decorative features: a completely black surface, flame-shaped dark patterns on the blade and socket, and identical gold inlays of bird-seal script on the socket, reading “For use by Prince Guang of Wu”. This indicates that the maker was Prince Guang of Wu, who is Helu, the King of Wu. Based on the inscriptions of the burial objects, the tomb owner was Zengsun Shao, who served as the "Grand Sima" of the Sui state, a position of military authority.

Zengsun Shao is not recorded in extant literature and should be the grandson of a certain Zeng Hou of the Zeng state. The reason why Prince Guang's halberd was buried with Zengsun Shao, and placed inside the coffin as a personal item, must involve an extraordinary historical event, likely closely related to the Wu-Chu War.