In the struggle among powerful feudal states for hegemony, large states annexed smaller ones, expanding their territories. However, the rulers of these large states had to enfeoff newly acquired lands to their meritorious ministers. As a result, the power of these ministers grew stronger. They frequently fought among themselves, causing domestic tensions within the great powers to intensify. All parties desired a temporary halt to the wars for supremacy.
For this reason, Xiang Shu (pronounced "shù"), a minister of the state of Song, traveled between the states of Jin and Chu as a mediator.
In 546 BC, Jin, Chu, and several other states held the "Conference of Disarmament" (Mi Bing Huiyi, where "Mi" is pronounced "mǐ," meaning cessation of hostilities) in the state of Song. At this conference, ministers from Jin and Chu, representing the northern and southern alliances respectively, made peace and established a covenant. It was agreed that, except for the two major powers of Qi and Qin, all smaller states would pay tribute equally to both Jin and Chu. Jin and Chu would share hegemony equally, and for more than fifty years afterward, no major wars occurred.
After King Ping of Chu, grandson of King Zhuang of Chu, ascended the throne, the state of Chu gradually declined. In 522 BC, King Ping of Chu decided to depose his original crown prince, Jian. At that time, Crown Prince Jian and his tutor Wu She were stationed at Chengfu (west of present-day Xiangcheng, Henan). Fearing Wu She's opposition, King Ping first summoned him, falsely accusing the crown prince of plotting rebellion. Wu She vehemently denied the charges but was immediately imprisoned.
King Ping simultaneously sent assassins after Crown Prince Jian and forced Wu She to write a letter summoning his two sons, Wu Shang and Wu Zixu, back to the capital so they could all be eliminated together. The elder son, Wu Shang, returned to Yingdu (northwest of present-day Jiangling, Hubei; "Ying" pronounced "yǐng"). He was executed alongside his father, Wu She, by King Ping of Chu. Crown Prince Jian, having received advance warning, fled to the state of Song with his son, Gongzi Sheng.
Wu Zixu, the other son of Wu She, also escaped from Chu. He rushed to Song and found Crown Prince Jian. Unfortunately, civil unrest broke out in Song, so Wu Zixu, along with Crown Prince Jian and Gongzi Sheng, fled to the state of Zheng, seeking Zheng's help for revenge. However, Duke Ding of Zheng refused. Desperate for vengeance, Crown Prince Jian conspired with some Zheng ministers to seize power from Duke Ding and was killed. Wu Zixu had no choice but to flee Zheng with Gongzi Sheng and seek refuge in the state of Wu (its capital in present-day Suzhou, Jiangsu).
King Ping of Chu had long ago issued a bounty for Wu Zixu's capture, ordering portraits of him to be hung at city gates throughout Chu and instructing officials to conduct strict inspections.
After escaping Zheng, Wu Zixu and Gongzi Sheng traveled by night and hid during the day, eventually arriving at the Zhaoguan Pass (north of present-day Hanshan County, Anhui), on the border between Wu and Chu. The guards at the pass conducted rigorous checks. Legend says Wu Zixu was so anxious he couldn't sleep for several nights, and his hair turned completely white from worry. Fortunately, they encountered a kind man named Dong Gao Gong, who sympathized with Wu Zixu and took him into his home. Dong Gao Gong had a friend whose appearance resembled Wu Zixu's. Dong arranged for this man to impersonate Wu Zixu and pass through the checkpoint. The guards captured the imposter, while the real Wu Zixu, with his hair now white and his appearance changed, went unrecognized and slipped through the pass.
After passing Zhaoguan, fearing pursuit, Wu Zixu hurried forward. Ahead lay a wide river blocking his path. Just as he was desperate, an old fisherman rowed a small boat toward him and ferried Wu Zixu across. Once across the river, Wu Zixu was profoundly grateful. He removed the precious sword at his side and gave it to the old fisherman, saying, "This sword was bestowed upon my grandfather by the King of Chu. It is worth a hundred ounces of gold. I give it to you now, as a humble token of my appreciation." The old fisherman replied, "The King of Chu has offered a reward of fifty thousand dan of grain for your capture and promises a noble title to whoever turns you in. If I don't covet such a reward or title, why would I want your sword?"
Wu Zixu quickly apologized to the old fisherman, retrieved his sword, and bid him farewell before continuing on his journey. Upon reaching Wu, Wu Zixu found that Prince Guang of Wu was planning to seize the throne. With Wu Zixu's assistance, Prince Guang assassinated King Liao of Wu (pronounced "liáo") and proclaimed himself king—this was King Helü of Wu (pronounced "hé lǘ").
After ascending the throne, King Helü appointed Wu Zixu as a senior minister to assist in governing the state. He also employed the general Sun Wu, a renowned military strategist skilled in warfare. Relying on Wu Zixu and Sun Wu, King Helü reorganized his armies and first annexed several neighboring small states. In 506 BC, King Helü appointed Sun Wu as commander-in-chief and Wu Zixu as deputy commander, personally leading a large army in an attack on Chu. They won victory after victory, utterly defeating Chu's forces and advancing all the way to Yingdu.
By then, King Ping of Chu had already died, and his son, King Zhao of Chu, had fled. Wu Zixu harbored intense hatred for King Ping, so he dug up his tomb and exhumed the king's corpse, whipping it fiercely. The Wu army occupied Yingdu.
Shen Baoxu, a man from Chu, fled to the state of Qin to plead for rescue. Duke Ai of Qin initially refused to send troops. Shen Baoxu stubbornly remained outside the Qin palace gates, weeping day and night for seven days and seven nights. Finally, Duke Ai of Qin was moved and said, "Though Chu may have been tyrannical and unjust, with such a loyal minister as this, how can we stand by and watch it perish?"
Duke Ai of Qin dispatched troops to rescue Chu, defeating the Wu army. Only then did King Helü withdraw his forces and return to Wu. Upon returning to his capital, King Helü credited Sun Wu with the greatest achievement. Sun Wu, however, unwilling to hold office, retired to his hometown. The book he left behind, *The Art of War*, is China's earliest outstanding military treatise.