As far back as the beginning of the year, Duan Qirui already had a premonition of his direct disobedience. He tried his best to prevent his direct family from going north, but he finally failed. At the beginning of the new year, it was planned to replace the Henan overseer Zhao Kui with Wu Guangxin, an Anhui figure, in order to block Wu Peifu's way back to the north (when the main force of Wu Peifu's army was in Hunan against the Guangzhou military government). The latter tended to be flattered, but he always opposed the connivance of the Anhui system against Japan. However, President Xu Shichang was afraid of causing a big change and did not allow it to be published. In order to gain the support of his direct family, Jin Yunpeng also expressed his opposition, so he did not forgive Duan Qirui and almost resigned.

On 7 March, Wu Peifu, commander of the 3rd Division of the Direct Army stationed in southern Hunan, demanded that the defense be withdrawn and go north, despite the direct telegram from the Beijing government. On March 18, Wang Chengbin, Xiao Yaonan, and Yan Xiangwen, commanders of the mixed brigade under Wu Peifu, began to withdraw their defenses and go north, and the Guangzhou Military Government continued to pay 300,000 yuan as a promotion fee. As an opposition, Qu Tongfeng, Chen Wenyun, Wei Zonghan, Li Jincai, and Liu Xun, the division commanders of the Anhui garrison near Beijing, sent telegrams, saying that the barracks were insufficient and refused to move the direct army.

At this time, Cao Kun was still just tempting, and when he saw that the Anhui system was fighting back directly, he didn't dare to press too hard, but both sides knew that a larger-scale war was about to begin, which was irreconcilable.

The "May Fourth Movement" brought the "Anfu Congress" controlled by Duan Qirui's government and the Anhui faction into disrepute, and gradually lost its prestige among the people. Looking at the achievements of Zhang Hanqing's "Anxi Army" in the northwest, Cao Kun and Wu Peifu's eyes became hot. Seeing that the situation was like this, the two thought that there was an opportunity, so they sent people out of the customs to actively lobby Zhang Zuolin, in order to achieve the trend of attacking the Anhui system between the north and the south of the direct line and the Feng line.

At this time, the Feng army had completed the reorganization of 10 divisions, and it was the time when the soldiers were full of food and talent. The stability of the four regions of Xing'an, Rehe, Chahar, and Mongolia and the achievements of the "Northwest Army" have brought the prestige of the autonomous government of the Northeast United Province to a new peak, and also caused the high-level officials of the Feng department to once again turn their attention to Guannai.

But for the olive branch thrown by the direct family, Zhang Zuolin weighed the pros and cons, and could not decide: on the one hand, it was the temptation to enter the customs to obtain benefits, and on the other hand, it was to offend the Japanese who were the supporters behind the Anhui lineage. Although he is a very patriotic warlord in his bones, he cannot ignore the influence of the Japanese at this time and place, with his strength and status. Wu Junsheng, an important ally in his life, was also reluctant to go out of the customs, and Wu insisted that "the department should be closed and wait for the coming day, although Liaodong is small enough to be king", and is currently taking it as a priority to wait and see the situation and hide and maintain obscurity.

Zhang Hanqing and Sun Liechen were supporters of the exit, and Sun Liechen believed that the main forces of the Anhui system were scattered all over the country and were easy to break. There was little resistance for the Feng army to go out of the customs, and it was not known whether they could take the opportunity to become the master under the influence of the Mongols and the influence of the countrymen. And Zhang Hanqing knew the quick victory of the Zhiwan War in history, and of course he advocated sending troops to prevent his direct family from sitting in the Beiyang government. He believed that the Japanese, because of their fear of Britain and the United States, their lack of domestic economic strength, the influence of the political climate, and the burden of the Far East intervention forces, were not yet able to intervene on a large scale, and could only symbolically express their opposition, so they were not afraid.

Zhang Zuolin was accustomed to Zhang Hanqing's advances, and he readily agreed, and in April, with Wang Naibin as the plenipotentiary, he discussed the conditions for forming an anti-Duan alliance with his direct family. The conditions given by Zhang Hanqing are:

The Beijing government was formed, and the chief of finance, agriculture and commerce, and transportation of the new government was designated by the Feng department;

Feng obtained the Chahar provincial capital of Zhangyuan (i.e., Zhangjiakou, which was defended by the Anhui army at this time);

The two places of Zhili Tangshan and Qinhuangdao surrounded by Rehe were merged into the Rehe Special Zone controlled by the Feng system to form Rehe Province;

The Suiyuan Special Region of the direct customary forces is classified as the Feng department;

The two factions of Zhifeng attacked Shaanxi together in the northwest, and the two sides were bounded by the Wei River, with the Northwest People's Army occupying the north and the Zhijun army occupying the south;

Tianjin is the demarcation point between the two forces, and both sides can station troops in Tianjin, but they must not interfere in Tianjin's civil affairs;

After the war, the Feng faction agreed and supported the direct ownership of the three provinces of Anhui, Shandong, and Zhejiang.

It was a broadly acceptable agreement: Shaanxi separated Gansu, which was controlled by the Feng family, from Hubei, which was directly controlled by the direct family, and it was fair to divide Shaanxi equally; If northern Shaanxi is owned by the Feng system, Suiyuan is surrounded by the Feng system of Gansu, Mongolia, and Chahar (the neighboring Shanxi is the unbreakable sphere of influence of another warlord, Yan Xishan); Tianjin is a place where all foreign forces gather, although there are benefits of customs, but they are often to blame, and the direct family does not have much interest; The two places of Zhili, which are close to Shanhaiguan, are in the place where the Feng system must connect Tianjin and Rehe, and the Feng army is bound to win and will not be negotiated. The direct line consolidated the territory of the Yangtze River basin and the north, and the Feng system took over a large area of land connecting the convenient passage between the northwest and northeast. It's a joy for all.

On May 17, Duan Qirui held an operational meeting in Tuanhe and ordered the border guards to concentrate in the area of Beijing, and Duan planned to station himself in Zhengzhou to meet the Wu army. In order to boost morale, on the 4th of the following month, Duan Qirui and Xu Shuzheng announced that they would mobilize to defeat the Southern Army.

Duan Qirui had just left, and on June 10, the Fengjun outside the gate was ordered to drive from Duliu Town in Zhili to Langfang through Tianjin.

On June 13----, Zhang Jingyao, the Hunan overseer of the Anhui system, was expelled from Hunan for all parties, and Beijing had no choice but to "relinquish his post as Hunan overseer and governor and temporarily stay in office."

On June 15, Wu Peifu and the brigade commanders of the Zhili Army, Wang Chengbin, Xiao Yaonan, and Yan Xiangwen, traveled from Zhengzhou to Baoding to meet with Cao Kun, the overseer of Zhili.

On July 4, Xu Shichang dismissed Xu Shuzheng from his post as a border envoy in the northwest, and dismissed the commander-in-chief of the frontier defense with Li Yuan's care, and the army under his jurisdiction was taken over by the Ministry of War.

On July 5, the Anhui overseer Ni Si rushed to Beijing, and Duan Qirui ordered the border guards to mobilize.

On July 6, the border guards dispatched to Changxindian and Langfang, and there were already signs of war.

Zhang Zuolin was already ready to beat the water dogs, but in order to paralyze Duan Qirui, he went to Tuanhe in person and persuaded Duan Qirui not to use soldiers. However, after receiving the "guarantee" that Zhang Zuolin would maintain the neutrality of the army, Duan Qirui thought that the victory was in his hands, insisted on going to war, and demanded that Wu Peifu be punished. Under this situation, Feng Yuxiang, the commander of the 16th Mixed Brigade of the direct line, led his troops to retreat from Taoyuan, Changde, and moved troops to Hankou Chenjiaji...

The battle of Zhiwan was inevitable, but the three mixed brigades of the Third Division led by Wu Peifu and the two divisions of Cao Kun's headquarters could not but have some scruples in the face of the Anhui army backed by the Japanese garrison in North China. At Wu Peifu's suggestion, on July 10, Cao Kun sent a telegram to the Beijing legation, asking it to pay attention to the fact that Japan was secretly assisting Duan. The United States, Britain, and France oppressed the Japanese envoy to express their attitude. On the 14th, the Japanese minister was forced to issue a declaration stating that he would never help the paragraph.

In order to cheer up his direct family, Zhang Zuolin sent a telegram to Cao Kun on July 11, saying that he had sent the 28th Division to enter the pass first, and the Fengjun in the pass sent Zhang Jinghui as the commander. He estimated that there were 70,000 or 80,000 troops in the Fengzhi coalition army in Guannai, which could cope with the war on the eastern and western fronts. And assured Cao Kun: "My life is close to each other, and at this critical juncture, I can't help but do my best to help." ”

After receiving the assurances of the Japanese that they would not help Anhui, and with the support of Feng in the rear, Cao Kun decided to fight against Duan Qirui, so the Zhiwan War began.