After Duke Wen and Duke Xiang of Jin, the royal power of the Jin state declined, and state affairs fell into the hands of several high-ranking ministers. By the late Spring and Autumn period, the Jin government was controlled by six ministerial families—Zhao, Wei, Han, Fan, Zhi, and Zhonghang—historically known as the "Six Ministers." Later, the Fan and Zhonghang families were eliminated. By the time of Duke Chu of Jin, only four ministers—Zhi Boyao, Zhao Xiangzi, Han Kangzi, and Wei Huanzi—held power, with the Zhi family being the strongest among them.
Duke Chu of Jin, unwilling to remain a puppet ruler, secretly sought troops from the states of Qi and Lu in an attempt to eliminate the Four Ministers. Unexpectedly, not only did Qi and Lu refuse to lend troops, but they also informed Zhibo Yao of the plan. Zhibo Yao then allied with the other three ministers to attack Duke Chu of Jin, who was forced to flee and later died of illness on the road. After Duke Chu's death, on Zhibo Yao's recommendation, the clansman Ji Jiao was installed as ruler, historically known as Duke Ai of Jin.
Zhi Boyao had a personal relationship with the father of Duke Ai of Jin, and he used this connection to influence and manipulate the duke, thereby seizing control of the overall situation in the state of Jin. With all power concentrated in his hands, Zhi Boyao grew increasingly arrogant and domineering, and his ambitions swelled. Unwilling to share power with the other three families, he aimed to swallow up Jin entirely and become the sole dominant force. His advisor suggested a scheme: under the pretext of Duke Ai's orders, demand land from the other three families, claiming it was needed to compete for hegemony against the increasingly powerful state of Yue. If they agreed to cede territory, it would gradually weaken them; if they refused, he could legitimately launch a military campaign against them. Zhi Boyao thought this plan was excellent and immediately put it into action.
The Han, Zhao, and Wei families received the notice of land requisition and knew that Zhi Boyao harbored ill intentions. Han Kangzi initially wanted to flatly refuse, but his retainer Duan Gui advised that Zhi Boyao was cunning, treacherous, and stubbornly self-willed; if his demand was rejected, he would surely launch a military attack. Moreover, his greed was insatiable, and besides approaching the Han family, he had likely made similar demands to the others. It would be better to wait for someone else to refuse and provoke an attack, then reap the benefits from the sidelines. Han Kangzi found this plan feasible and decided to endure a small loss for now while biding his time, so he sent an envoy to deliver a town of ten thousand households to Zhi Bo.
Zhi Bo saw that Han Kangzi had handed over land so easily and was filled with joy, waiting for the Wei family to deliver their land as well. Wei Huanzi, of course, was unwilling to give land to Zhi Boyao. His advisor, Ren Zhang, analyzed the situation for him, saying that since Zhi Boyao had obtained land so effortlessly, he would become even more arrogant and overbearing, believing himself invincible, which would inevitably lead him to underestimate his enemies. Meanwhile, the families who had lost their land could unite to confront a single arrogant and reckless foe, and the outcome would be obvious. Therefore, he advised Wei Huanzi not to begrudge the land for now, but to wait until the situation turned and the Zhi family lost power. So Wei Huanzi also gave Zhi Boyao a town of ten thousand households.
Having obtained two towns of ten thousand households without any effort, Zhi Bo was extremely pleased and demanded the territories of Cai and Gaolang from Zhao Xiangzi. Zhao Xiangzi had long held a grudge against Zhi Boyao. Years earlier, when the Zhi family led an army to attack the state of Zheng, Zhao Xiangzi, then still the heir of the Zhao family, had been insulted by Zhi Boyao upon entering the capital, fueling deep resentment. Later, Zhi Boyao even interfered in the internal affairs of the Zhao family, attempting to undermine Zhao Xiangzi's position as heir, which only intensified his hatred. This time, when Zhi Boyao demanded land, Xiangzi flatly refused. In response, Zhi Boyao immediately allied with the Han and Wei families, intending to use the combined forces of the three families to wipe out the Zhao clan in one decisive strike.
Zhao Xiangzi, seeing that the situation was unfavorable for him, gathered his followers to discuss retreating to avoid the enemy's advance, ultimately deciding to fall back to Jinyang. The Zhao clan had managed Jinyang for many years to prepare for unforeseen circumstances. Earlier, when the Fan and Zhonghang clans supported Handan's rebellion, Zhao Jianzi had retreated to Jinyang for protection. Zhao Jianzi had specifically instructed Xiangzi that if the state of Jin faced danger, he could retreat to Jinyang. After Zhao Xiangzi succeeded to the position, he reduced taxes for the people of Jinyang, benefiting them and winning their support. For the Zhao clan, this was their most reliable stronghold.
After retreating to Jinyang, Zhao Xiangzi discovered that the city had strong fortifications and ample supplies, but because they had withdrawn in haste, they lacked sufficient weapons for defense. His advisor Zhang Mengtan told him that Jinyang had originally been built with military preparedness in mind, so the materials used to construct the palaces could be repurposed to make weapons. They then sawed down the bronze pillars from the palaces to forge arrowheads, swords, and halberds, and used the materials from the palace walls to make arrow shafts, thus producing an adequate supply of weapons. Now they only had to wait to engage the allied forces of the three families in battle.
In 454 BCE, Zhi Boyao led the armies of the Han and Wei families to attack Jinyang, but after three months of fierce fighting, they still could not capture it, and after besieging it for over a year, they still failed to take it. Watching the war drag on, Zhi Boyao grew increasingly anxious. One day, while surveying the terrain outside the city, he saw the Jin River flowing past Jinyang from the northeast and suddenly had an idea: if he diverted the river's course to the southwest, wouldn't he be able to flood Jinyang? With this plan in mind, he quickly ordered his soldiers to dig a canal beside the Jin River leading straight to Jinyang and build a dam upstream to hold back the water.
Soon, the rainy season arrived, and with upstream dams blocking the flow, the Jin River swelled as water accumulated, causing its level to surge dramatically. Zhi Boyao, seeing the time was ripe, ordered the dams opened to release the floodwaters. The raging torrents roared into Jinyang City, instantly turning it into a vast ocean. People's homes collapsed under the force of the water, and frogs leaped in and out of the stoves where they once cooked meals; the residents had to hang their pots to prepare food. Eventually, when food supplies ran out, the city descended to the point of exchanging children for meat to survive. Despite this, the people remained steadfast in supporting Zhao Xiangzi's defense, refusing to surrender.
Zhi Boyao, feeling that the fall of Jinyang was imminent, proudly took Wei Huanzi and Han Kangzi to inspect the floodwaters. Extremely pleased with his strategy, he said arrogantly, "Now I realize that water can also destroy a country." This remark startled Wei and Han, who immediately thought of their own cities: Anyi, Wei's city, surrounded by the Fen River; and Pingyang, Han's fief, encircled by the Jiang River. They realized that if Zhi Boyao could use the Jin River to flood Jinyang, he could also use the Fen River to flood Anyi and the Jiang River to flood Pingyang. Thinking that today's Jinyang could well be tomorrow's Anyi or Pingyang, Wei Huanzi secretly nudged Han Kangzi with his elbow, and Han Kangzi responded by stepping on Wei Huanzi's foot—a silent understanding that they were now inclined to turn against him.
Zhi Boyao was happily thinking that he would soon breach the city of Jinyang, and paid no attention to the subtle movements of the leaders of Han and Wei. However, his subordinate Xici noticed that the rulers of Han and Wei looked worried. He analyzed that originally the three families had agreed to divide Zhao's land after destroying it, but now that Jinyang was about to fall, the two rulers showed no joy at all, which surely meant they were concerned about their own interests. With such concerns, they would definitely rebel. Zhi Boyao did not believe Xici's words and even told them to Wei Huanzi and Han Kangzi. The rulers of Han and Wei naturally denied it, and Zhi believed them. To avoid disaster, Xici asked Zhi Boyao to send him as an envoy to the state of Qi.
The situation in Jinyang City grew increasingly dire, and Zhao Xiangzi feared that even with the people's support, the city could not hold out much longer. In this moment of crisis, he conspired with Zhang Mengtan and sent him to persuade the rulers of Han and Wei to switch sides. Zhang Mengtan secretly slipped out of the city and met with the two hesitant lords. The three quickly reached an agreement, plotting to coordinate from within and without to eliminate the Zhi clan together, then divide the Zhi family's territories equally among themselves.
Zhao Xiangzi had already reached an agreement with the Han and Wei families, while Zhi Boyao, fully believing that Jinyang City would soon fall, remained completely unaware and slept soundly. The next night, Zhao Xiangzi sent soldiers to quietly kill Zhi Boyao's guards at the dam, then breached the western side of the embankment, causing the Jin River to flood back into Zhi Boyao's military camp. Chaos immediately erupted in the camp; Zhi Boyao, awakened by the commotion from his deep sleep, only then realized the camp was flooded. Unaware of what was happening, he panicked, and at that moment, shouts of battle arose from all directions. Zhao's forces charged out from the city, while the Han and Wei families attacked from both flanks, breaking into Zhi Boyao's camp. Zhi's army was utterly defeated, and Zhi Boyao himself was killed.
After this battle, the Zhi clan was annihilated, and the Zhao, Wei, and Han families divided its territory.
In 403 BC, the three houses of Han, Zhao, and Wei sent envoys to King Weilie of Zhou, requesting to be enfeoffed as feudal lords.
The Zhou king, already a ruler in name only, knew that even if he disagreed it would be useless and only embarrass himself, so he might as well comply, and thus officially enfeoffed the three houses of Han, Zhao, and Wei as feudal lords. After the "Partition of Jin by Three Houses," Chinese history entered the Warring States period. The state of Jin, one of the Five Hegemons of the Spring and Autumn period, perished, and together with the four great powers of Qin, Qi, Chu, and Yan, Han, Zhao, and Wei formed the historical "Seven Warring States."