Combining the vertical means uniting the weak to attack the strong. Since the Shang Dynasty changed the law, the state of Qin has been thriving, and has successively conquered the Eastern Zhou, Han, Wei and other countries, and seized a large area west of the Wei River. Wherever its troops went, most of the nations were defeated. Because the Qin State is located in the western border, with the Xiongnu and Yiqu in the north, Di and Qiang in the west, and Ba and Shu in the south, the Qin State is also regarded as a semi-Rongdi country by the Kwantung States and has been ostracized. With the strength of Qin, it was extremely difficult for other countries to destroy Qin on their own, so there was a cooperation model of "joining forces" to attack Qin. In history, the six Kwantung countries launched a total of five "joint vertical" attacks on Qin. 
The first time: Chu, Yan, Han, Wei, and Zhao jointly attacked Qin In 325 BC, Qin Hui Wenjun followed the precedent of Wei and Qi as the "Xuzhou Xiangwang", and asked the kings of Wei and Han to enter Qin and elect Qin Jun as king, and Qin also recognized the titles of Wei and Han kings. Subsequently, under the impetus of Zhang Yi, who was the prime minister of Qin and Wei, the three kingdoms of Qin, Wei, and Han jointly went east and launched an attack on Qi, a first-class power that was comparable to Qin at that time. However, this time Lianheng was defeated by Qi State, and Zhang Yi's Lianheng strategy was frustrated. 
After the failure of the Qi attack, King Wei Hui broke away from the influence of Qin and expelled Zhang Yi back to Qin. In order to consolidate political relations with the five states of Qi, Chu, Yan, Zhao, and Han, King Hui of Wei reappointed Gongsun Yan, who advocated the strategy of "joint verticalization", as prime minister and switched to the camp of joint vertical. In 318 BC, Gongsun Yan, the new prime minister, launched a "joint vertical" strategy, united the countries of the Kwantung region, and planned the first "War of the Five Kingdoms against Qin". Although Chu, Yan, Han, Wei, and Zhao participated in the first joint expedition, and elected King Huai of Chu as the commander, in fact, only Zhao, Wei, Yan, and Han sent troops to participate, and Chu did not send troops. In addition, since the Yan State was not greatly threatened by Qin, although it participated in the joint investigation, it had the same negative attitude as the Chu State, and the sending of troops was only a symbolic participation. 
The mighty Four-Nation Coalition fought all the way to the Qin's strategic Hangu Pass, and due to the Qin army's fierce resistance, the coalition army was finally defeated by the Qin army outside the Hangu Pass. The following year, Qin defeated the allied forces of Zhao, Wei, and Han in Xiuyu, beheading more than 80,000 people. The first joint attack on Qin was a complete failure. 
The second time: Qi, Han, and Wei jointly attacked the six states of Qin and Kwantung Although it was clear that Qin would be their common opponent, because Qin tried his best to sabotage the alliance between the six countries, he instigated the countries to attack each other in order to weaken the strength of the six countries. Therefore, the conflicts between the six countries of the Kanto region have also occurred one after another. In 301 BC, Qi, Wei, and Han jointly attacked Chu and defeated the Chu army at Chuisha, and Han and Wei took the opportunity to occupy a large area of Chu land. The victory of the Triple Alliance made the Qin State extremely uneasy. In order to break up the alliance of the Three Kingdoms, Qin proposed to take King Qin's brother Jingyang Jun into Qi as a hostage and reconcile with Qi. At the same time, it is hoped that Meng Yanjun, a native of Qi, will be the prime minister of Qin, and Meng Yanjun, who has always supported the joint attack on Qin, will be controlled in the Qin State, and the formation of the alliance to attack Qin will be dismantled. 
At the same time, Qin's expansion did not stop. After occupying a large area outside the Qinling Mountains, he attacked 25 cities of Zhanyiqu in the north. Then he turned to attack the hinterland of the Central Plains, defeated the Chu army, annihilated more than 50,000 Chu troops, and occupied more than 10 cities. The expansion of the Qin state made the three kingdoms of Qi, Wei, and Han highly nervous, so they decided to take advantage of Qin's exhaustion from the long war. In 298 BC, the Three Kingdoms joined forces to attack the Qin state. This joint attack on Qin lasted for three years, and finally the alliance of the three kingdoms invaded Hangu Pass, forcing Qin to admit defeat and return to the previously occupied areas of Wei Hewai, Fengling, and the Wukou in Korea, and conclude a treaty. The second joint attack on Qin ended in Qin's defeat. 
The third time: Yan, Qi, Wei, Han, and Zhao attacked Qin and Qin After Wei Ran came to power, he continued to implement the strategy of "connecting horizontals" and actively won over the eastern power Qi in order to compete with the five states of Chu, Zhao, Yan, Wei, and Han. In October 288 BC, King Zhao of Qin proclaimed himself the Western Emperor in Yiyang and ruled the West; Yao honored King Qi as the Eastern Emperor, ruled the East, and prepared to unite Qi to attack Zhao. Although the target of Qin's attack was Zhao, the most nervous were Han and Wei, and their situation between Qin and Zhao was indeed quite awkward. In order to prevent Qin from attacking Wei when he attacked Zhao, King Hui of Wei ceded Ge Xin and Yin Cheng to Zhao on the one hand, so as to form an anti-Qin alliance with Zhao, and on the other hand, sent strategists to sabotage the alliance between Qin and Qi, especially Su Qin, a well-known supporter of the alliance, also participated in the lobbying of Qi for the benefit of Yan, and successfully pulled Qi into the camp of Zhao and Wei. The three kingdoms of Qi, Zhao, and Wei eventually allied with A, and the king of Qi took the initiative to cancel the emperor's title, putting Qin in a dilemma. 
In addition, Zhao Xiangguo Fengyang Jun Li Dui ran between the six Kwantung countries, taking advantage of the contradictions between the countries and Qin, and finally contributed to the situation in which the five states of Zhao, Qi, Wei, Yan, and Han jointly attacked Qin. However, due to the small calculations of the countries involved in the joint alliance, Qi had a negative attitude and did not contribute to the work, and Yan and Han also seemed to be separated, and the five-nation alliance army marched to Xingyang and Chenggao and began to watch each other, and no one was willing to take the initiative to attack. In order to destroy the alliance of the five kingdoms, Qin took the initiative to give up the emperor's title, and returned the previously occupied Wen, Yi, and Gaoping to Wei, and returned the princes and Fu Yu to Zhao. Although Qin's series of moves succeeded in causing the Five Powers Alliance to retreat, strategically, Qin still suffered a serious setback in the third joint attack on Qin by the Six Kwantung Powers. 
Fourth: Zhao, Chu, Han, Yan, and Wei attacked Qin in 249 BC, and King Xiang of Qin Zhuang appointed Lü Buwei as Qin Xiang. After Qin destroyed the Eastern Zhou Dynasty, the Qin general Meng Wei led his army to conquer the cities of Chenggao and Xingyang in Korea, and merged them with the territories of the Western Zhou and Eastern Zhou to form Sanchuan County. Subsequently, the Qin army attacked Wei in a big way, and the Wei capital Daliang was already in danger. The anxious King of Wei immediately sent someone from Zhao to invite back the Xinling Emperor Wei Wuji, and worshiped him as the general of Wei to command the war against Qin. Wei Wuji knew very well that he could not resist the attack of Qin with the strength of Wei alone, so he chose to unite with various countries and unite to resist Qin. The first thing Wei Wuji chose to unite was Zhao Guo, because Wei Wuji had stolen talismans to save Zhao in danger, so Zhao Guo reciprocated and decided to send troops to rescue Wei without hesitation. 
And the three kingdoms of Chu, Han, and Yan also admired the prestige of Xinlingjun, and sent troops to cooperate with Wei to fight against Qin. The situation of the five kingdoms of Wei, Zhao, Chu, Yan, and Han joining forces to resist Qin for the fourth time was formally formed. In the face of the joint efforts of the Five Kingdoms to resist Qin, the Qin general Meng Fu realized that the strength of the Five Nations Alliance, coupled with the prestige of Wei Gongzi's unscrupulousness, if there was a head-on decisive battle, the Qin army would inevitably suffer heavy losses. So a strategic retreat was carried out, and the battle was retreated. When the Five Nations Alliance pursued the Qin army to Hewai, the two armies were engaged and the Qin army was defeated and was forced to retreat into the Hangu Pass, and the situation was extremely favorable to the Five Nations Alliance. However, due to the rapid progress of the coalition forces, they faced great difficulties in terms of troops and logistical support, and they were no longer able to attack Hangu Pass and attack the hinterland of Qin. The fourth joint attack on Qin by the five Kwantung states ended in victory. Fifth: Zhao, Chu, Han, Yan, and Wei jointly attacked Qin After the victory of the fourth joint attack on Qin, the six Kwantung countries fell into a situation of attacking each other. Taking advantage of this opportunity, the state of Qin immediately began to unfold, and its sword was pointed directly at Han and Wei. Han and Wei ** were Qin's opponents, and they lost more than 20 cities in a row as soon as they started fighting, especially after losing the strategic place of Chaoge, after the borders of Qin and Qi were connected, the joint vertical of Shandong countries was cut off. 
In order to get rid of this unfavorable situation, the Kwantung countries formed a coalition army of Zhao, Wei, Han, Chu and Yan to resist Qin for the fifth time in 241 BC, that is, in the sixth year of the reign of King Qin, and the Zhao general Pang Xuan commanded to attack Qin. This joint attack on Qin had the most obvious impact on Qin. The forces of the Five Nations Coalition broke into Hangu Pass and advanced to a land only seventy or eighty miles away from Xianyang City. However, due to the stubborn resistance of the Qin army stationed in Yudi, the coalition forces were unable to overcome it for a long time. It won valuable time for the Qin army to readjust its deployment. Subsequently, after Huang Xie, the commander of the Five-Nation Alliance, learned that the Qin army would concentrate its main force to eliminate the Chu army in the coalition army, he took the Chu army to break away from the coalition army and return to Chu overnight. The commanders of the Qin army, Wang Jian and Meng Fu, immediately led the army to storm the Zhao army camp, although the battle did not break the Zhao army camp. However, a rift had already appeared between the five kingdoms of the alliance, and the retreat of the Chu state without a fight made the coalition army lose everything. As a last resort, Zhao, Han, Wei, and Yan had to collect their troops and go home. The fifth joint attack on Qin ended with the victory of Qin.
The six states of Zhao, Han, Wei, Yan, Chu, and Qi joined forces to resist Qin, which lasted for more than 100 years. After the defeat of the fifth joint attack on Qin, the six countries were never able to form a joint column camp again. After Qin Wangzheng became pro-government, he adopted various strategies to break through, and did not leave any chance for the six Kwantung countries to join forces.