In November 1930, the smoke of the Central Plains War had just dissipated, and in this battle, the Northwest Army, which had once traversed the northwest and supported hundreds of thousands of troops, fell apart in an instant, and Feng Yuxiang, as the main backbone, also issued a telegram under the pressure of Chiang Kai-shek, announcing that he had gone to the wilderness to escape the world. However, although Chiang Kai-shek forced Feng Yuxiang away, in order to prevent the Northwest Army from making a comeback, he ordered his deputy commander-in-chief Zhang Xueliang to personally go to Beiping and take full responsibility for the reorganization of the remnants of the Northwest Army. Therefore, there is only one way in front of him now, that is, to find a general of the Northwest Army who is "recognized by all three parties" as soon as possible to help him complete the task of "peacefully integrating the Northwest Army".
After arriving in Beiping, Zhang Xueliang came to the headquarters to seriously consider this issue, and believed that the candidates must meet three conditions: First, they must have a mass base in the Northwest Army so that they can control the situation; second, they must have Feng Yuxiang nod their heads so as not to fall into the hands of others in the future; third, they must be trustworthy people, otherwise they are likely to defect in the future.
First of all, Sun Liangcheng, who was one of Feng Yuxiang's "Five Tiger Generals", had served as the commander-in-chief of the Nationalist Army to aid the Shaanxi Army in the Northern Expedition War, responsible for fighting against the Zhensong Army in the Shaanxi region, although he was a tough general in the Northwest Army, he was a brave and less strategic, indecisive person, plus his concubine troops had basically been reimbursed in the Central Plains War, if he let this "light rod commander" rush forward, the effect might be counterproductive, so Sun Liangcheng was first denied by Zhang Xueliang as soon as he appeared. The second was Liu Ruming, who was one of Feng Yuxiang's "Thirteen Taibao", who had come to prominence before the "Wuyuan Oath Division", fought bloodily with Wu Peifu's troops for several months, and did not let him make a breakthrough, and finally when he completed the task and returned to Wuyuan, his troops were still strong and strong, which made his colleagues look at him with astonishment, but the biggest "problem" of this person was that he was not qualified enough, there were too many "old chiefs" in front of him, and Zhang Xueliang was worried that he could not control the situation, so he had to abandon Liu Ruming.
Finally, after careful consideration, Zhang Xueliang chose Song Zheyuan, first of all, from the perspective of seniority, Song Zheyuan is one of Feng Yuxiang's "Five Tiger Generals", belonging to the most constrained generals, and compared with others, he also has Feng Yuxiang's "shadow" in life, he can share happiness and hardship with ordinary soldiers, very popular, plus he is not greedy for money, and he pays great attention to fame, so Zhang Xueliang attaches more importance to Song Zheyuan as a candidate. On December 24, 1930, Zhang Xueliang summoned Song Zheyuan, and then the two began to discuss the aftermath of the Northwest Army, because he was a "general of the defeated army", Song Zheyuan was also eager to "pull back" the "family foundation" of the eldest brother Feng Yuxiang by himself, so he gladly accepted Zhang Xueliang's appointment and began to collect the remnants of the Northwest Army scattered everywhere.
Four months later, this "lone army" was peacefully incorporated by Zhang Xueliang and given the name of the Third Army of the Northeast Border Defense Army, with Song Zheyuan as its commander and Qin Dechun and Liu Ruming as its deputy commanders. In June 1931, Song Zheyuan's unit was renamed the Twenty-ninth Army of the National Revolutionary Army, stationed in the southeastern region of Jin, although it seemed to have a foothold, but this place belonged to Yan Xishan's territory, so the Twenty-ninth Army lived a life under the fence, because Yan Xishan and Zhang Xueliang ignored it, resulting in poverty in the army, and the soldiers were ragged, like beggars. After the September 18 Incident, Song Zheyuan and seven other generals sent a telegram to fight against Japan, saying that "it is better to die in battle than to be a slave to the country", and then under the strong recommendation of Zhang Xueliang, Song Zheyuan's troops moved to Chahar, it is said that when marching, because the soldiers were wearing a tattered shirt and were afraid of being regarded as bandits, Song Zheyuan chose to set out at night, so it can be seen that although the Twenty-ninth Army at that time was very embarrassed in life, their backbone was also very admirable.
After arriving at the destination, Song Zheyuan first put forward the slogan of "no civil war, the muzzle of the gun is external", and then actively reorganized the army to train troops and prepare for future operations against Japan, and it was less than half a year after that, the Great Wall War of Resistance broke out, the Twenty-ninth Army rushed to the front, and finally became famous in the Battle of Xifengkou.