Since Qin Xiaogong appointed Shang Yang to change the law, the national strength of the Qin State has rapidly become stronger. At this time, the power of Wei had declined, and the strength of Qi and Qin was comparable. Due to the inter-border borders of the territories of the states, wars and diplomatic conflicts often occurred between the vassal states. In order to survive and develop in this environment, the two great powers of Qin and Qi launched a struggle against each other to win allies and isolate enemy countries. Han, Zhao, Wei and other countries were also divided into two major factions, the United Qin Anti-Qi and the United Qi Anti-Qin, thus launching joint vertical and horizontal activities.
The so-called vertical and horizontal, geographically speaking, is dominated by Han, Zhao and Wei, with Yan in the north and Chu in the southThe east is connected with Qi, the west is connected with Qin, and the east and west are connected horizontally. Strategically speaking, it refers to the situation of uniting multiple weak countries against one strong country and preventing the strong country from annexing the weak country. Lianheng refers to the formation of alliances with strong countries against other weak countries. in order to survive. The vertical can be aligned with the Qin and the horizontal, and the horizontal can be aligned with the Qin or the horizontal. This is the so-called "Chao Qin and Twilight Chu".
At that time, there were some activities among the vassal states, either taking longitudinal or horizontal, with their incorruptible tongues to impress the princes and kings, and they were called them"Vertical and horizontal family"。The most famous of these are Gongsun Yan, Zhang Yi and Su Qin. By lobbying and giving advice to various countries, they have created a situation of cooperation between countries.
In 340 BC, Gongsun Yan held the position of rhino head in Wei State, and King Wei Hui and King Qi Wei met in Xuzhou and recognized each other as kings, known as "King of Xuzhou" in history. King Chu Wei was also very angry about this. Gongsun Yan suggested that King Hui of Wei make friends with Qi on the surface, and secretly befriend Chu State, so that Qi and Chu would fight openly and secretly, and Wei State would reap the benefits of the fisherman. King Wei Hui followed his advice. In 333 BC, King Chu Wei led a large army to attack Qi, and Zhao and Yan also took the opportunity to send troops to attack Qi. The state of Qi was defeated.
Subsequently, Gongsun Yan left Wei and went to Qin as an official. In 330 BC, Gongsun Yan led the Qin army to march towards Wei, and Qin recovered the Hexi region that had been captured by Wei. Later, the king of Wei sent Gongsun Yan's classmates with a lot of money to lobby him, so that he could persuade the king of Qin to release Wei. Gongsun Yan was a native of Wei, so he deliberately gave Wei a way to live. Zhang Yi saw through his plan and told the King of Qin about it, and the King of Qin was furious and directly removed Gongsun Yan's official position.
After leaving the Qin state, Gongsun Yan returned to the Wei state and became a general. At this time, Wei's national strength had declined. As a result, Gongsun Yan wanted to win by winning by co-opting other countries together. In 325 BC, Gongsun Yan united with Qi to attack Zhao, and Zhao was defeated. After that, Wei repaired relations with Han, Zhao, and Chu, and finally formed a friendly situation between Wei and Han, Zhao, Qi, and Chu. The emergence of the trend of convergence and longitudinal caused a high degree of vigilance in the Qin State, and Zhang Yi of the Qin State successfully cracked the Three Kingdoms Alliance. In 323 BC, Gongsun Yan co-opted the four kingdoms of Han, Zhao, Yan, and Zhongshan and launched the "Five Kingdoms Prime Minister" to confront the Qin state, but achieved nothing.
In 318 BC, Zhao, Chu, Wei, Han, and Yan jointly attacked the Hangu Pass of Qin, and the allied forces were defeated. Gongsun Yan could only leave Wei and prepare to go to Korea. Before leaving, he persuaded King Wei Xiang to let Tian Wen, the son of Qi, come to Wei to be the prime minister, and then went to Korea to become the prime minister. In 315 BC, Qin attacked the Central Plains region of Han and defeated the Han army at Anmen, and Gongsun Yanhe's longitudinal strategy failed again.
Gongsun Yan was the initiator of Hezong and a very strategic person, and his failure was not due to a problem with strategy, but because the kings of various countries had their own evil intentions and could not unite as one.