After Zheng Dan arrived in Longcheng, he was very happy to walk around every day, especially interested in the military camp, and the rest of the time was to accompany Xi Shi to walk around the city, this day Long Hui was checking in the arsenal, Zheng Dan came to find Long Hui, the general slave likes all kinds of weapons, especially the sword, and wants to ask the general for a handle, no problem, you go to the arsenal to choose, Zheng Dan went in and chose an Assyrian sickle. I practice swords every morning and evening. In 371 BCE, the Marquis of Wei died without appointing an heir to the Wei state, and chaos ensued in the country, and his sons Wei Fu and Wei Huan fought with each other.

In July of that year, Wei Huan fled to Handan and asked Zhao Chenghou to send troops to fight for his return to China. In 369 BC, Gongsun Qi, the doctor of Wei, also entered Korea from Song through Zhao to meet Han Yihou and persuade him.

Han Yihou was very happy to hear this, so he joined forces with Zhao Chenghou to attack Wei. Marquis Zhao Cheng and Marquis Han Yi personally led the armies of the two countries and joined forces to attack Wei. The coalition forces marched towards Anyi, the capital of Wei. Wei Fu sat in the capital and hurriedly sent the Wei army to meet the battle in Xunze. The Han and Zhao coalition forces defeated the Wei army in Yu Xunze, and then besieged Anyi.

At this time, Han Yihou and Zhao Chenghou had a disagreement, and Zhao Chenghou advocated getting rid of Wei Jun, supporting Wei Jun, and ceding the land and retreating. Han Yihou thought that this would be regarded as greedy by others, and he advocated splitting Wei into two countries, so that Wei was not stronger than Song and Wei, and Han and Zhao would no longer have Wei in the future.

Both sides are stubborn. Han Yihou was displeased, so he led the Korean army to leave at night. Marquis Zhao Chenghou saw that the Zhao army was lonely and could no longer fight, so he also led the army to withdraw. The coalition forces broke down without a fight, and the siege of Anyi was lifted. Wei Fu killed Wei Xuan and established himself as the king, for the king of Wei Hui.

In 363 BC, Qin sent troops to attack Shaoliang of Wei, and the combined forces of Zhao and Korea sent troops to rescue Wei. In 362 BC, the general of Wei defeated the Han and Zhao coalition forces on the north bank of the muddy water, and captured the general of Zhao Le Zuo. King Wei Hui rewarded him with millions of acres of land, and his uncle excused himself, saying that it was Wu Qi's teaching in the past, and now it is the work of his subordinates Ban Ning and Xiang Xiang. So Baning and Jiaoxiang were rewarded with 100,000 mu, Wu Qi's descendants were rewarded with 200,000 mu, and Uncle Gong was rewarded with 400,000 mu. Qin took advantage of the battle between Wei and Han and Zhao in the muddy water, and took Shu Changguo as his general, attacked Shaoliang of Wei again, defeated the Wei army, captured its main general Gongsun Xuan, and occupied Fanpang.

Although Wei defeated Han and Zhao, they were defeated by Qin.

The Wei state became powerful in the early Warring States period due to the reforms of Marquis Wen of Wei, which caused the other princes to be wary. In 356 BC, Marquis Cheng of Zhao met with King Wei of Qi and Marquis Huan of Song in Pinglu to show goodwill, and made an alliance with Duke Wen of Yan in A. As a result, Wei began to have the possibility of being attacked by various countries, so Wei wanted to find an opportunity to break through in order to relieve this crisis. Zhao attacked Weiguo and captured Qi and Fuqiu. This made Wei feel more threatened, because Wei was a protectorate of Wei, and Wei could not sit idly by, so he immediately united with Song to send troops to help defend the counterattack, and the alliance of Wei Wei and Song came straight to Handan, the capital of Zhao, and Zhao was forced to defend behind closed doors, and sent people to Qi for help. The coalition forces then besieged Handan, hoping to annihilate Zhao in one fell swoop in order to lift the situation of being surrounded by other countries. However, at the same time, the Qin State took advantage of the absence of the main force of the Wei army to attack the land of Shaoliang in Hexi and take it, and the danger of the Wei State being besieged in this war became even greater.

When King Qi Wei learned that Zhao was besieged, he wanted to send troops immediately, but the general Duan Ganpeng advocated delaying the dispatch of troops and taking "inheriting the disadvantages of Wei" as the strategic policy. That is, to attack Xiangling south with a small number of troops first, in order to create a false image, which can indicate assistance to Zhao, and can also contain and exhaust the Wei state. When the Wei army captured Handan and both Wei and Zhao were unable to fight again, they would give a frontal attack. King Qi Wei accepted this proposal, and when the two armies of Zhao and Wei had been holding each other for more than a year and Handan City was about to fall, he appointed Tian Ji as the commander and Sun Bin as the military advisor to lead the main force of the Qi army to aid Zhao.

At the beginning, Tian Ji planned to go to Handan to fight a decisive battle with the main force of the Wei army and solve the siege of Handan. However, Sun Bin believed that this was not conducive to the Qi State, so he proposed more innovative and feasible methods, namely "criticizing the hypothesis" and "speeding away". "Criticizing and attacking the weak" means avoiding the real and attacking the weak, attacking it will save it, so that the enemy will have to worry about the future, and the siege of the front line will be automatically lifted. "Rushing to the Great Beam" is to attack the heavy city of Wei with lightning speed, in order to cut off the transportation arteries of Wei and attack its unpreparedness. In this way, the Wei army will definitely return to the division to save itself, and the Qi army can take advantage of its exhaustion to defeat the Wei army in one fell swoop, and the siege of Zhao will be automatically lifted. However, Wei reversed the situation and allied with Korea to attack the Qi army, which was still besieging Xiangling, and the Qi army was defeated in this battle, so King Qi Wei withdrew his troops and asked Chu to mediate. The Qin army took advantage of the battle between Wei and Qi to attack Wei, and Wei had to sign a peace treaty with Qi because of Qin's sneak attack. As a result, in 351 BC, Wei returned Handan to Zhao, and the Qi-Wei War ended temporarily, but it was not long before Qi actually replaced Wei's supremacy.