In 1936, Chiang Kai-shek insisted on the civil war, he ordered Zhang Xueliang and Yang Hucheng to also suppress the Communists, but before that, Zhang Xueliang repeatedly raised objections, asking him to abandon the civil war and unite with the Communists, but Chiang Kai-shek did not pay attention to his heart and was stubborn, at this time Zhang Xueliang and Yang Hucheng had begun to make contact with the Communists, a big plan was in the making, and Chiang Kai-shek saw that Zhang Xueliang and others did not follow, and had to personally go to Xi'an to supervise the war, and did not expect that there was a "Xi'an Incident". Chiang Kai-shek was detained by Yang Hucheng and Zhang Xueliang by force in order to make him agree to unanimously resist Japan, which is also the next strategy after repeatedly advising Chiang Kai-shek unsuccessfully!

Later, after several talks between Zhou Enlai, Soong Ziwen, Soong Mei Ling, and others, Chiang Kai-shek was forced to sign a sign agreeing to stop the civil war and unanimously resist Japan, and Zhang Xueliang and Yang Hucheng also decided to let Chiang Kai-shek return to Nanjing, and even Zhang Xueliang felt that the matter had been resolved and had achieved his original intention of "military advice", but after all, Chiang Kai-shek was still the leader of the Kuomintang, and he would lead the anti-Japanese resistance in the future.
However, unlike the history we know, Chiang Kai-shek actually advised him not to escort himself back at this time. Some people will say that since Chiang Kai-shek initially advised Zhang Xueliang not to send him, because that period was in a sensitive period, Chiang Kai-shek could not kill and detain Zhang, which would cause another wave of turmoil. Many people have doubts, since Chiang Kai-shek is not ready to detain him, what else can not go? If Zhang Xueliang arrived in Nanjing, the matter would not be decided by Chiang Kai-shek, and the situation at that time was very complicated.
What is the complexity of the situation? First of all, there were contradictions and disputes within the Kuomintang; Zhang Xueliang also offended many people within the Kuomintang, and many Kuomintang elders had a very good opinion of Zhang Xueliang because of this incident, hoping to severely punish Zhang Xueliang and Yang Hucheng, and this was something that Chiang Kai-shek could not influence.
If Zhang Xueliang escorted Chiang Kai-shek back to Nanjing, under the pressure of the Kuomintang, he would certainly not be casually put back, so the Northeast Army would definitely lose its main backbone and launch an attack on the Central Army, which would then cause a civil war. The third is the personal relationship between Chiang Kai-shek and Zhang Xueliang, after all, Zhang Xueliang once turned to him, so that he completed the Northern Expedition ahead of schedule, unified China, and during the Central Plains War, he was indispensable to his credit. Zhang Xueliang did not go to Nanjing, it was okay, went to Nanjing, Chiang Kai-shek will ride the tiger difficult!
But later Zhang Xueliang still returned to Nanjing with Chiang Kai-shek, and at the beginning of the place where Zhang Xueliang stayed, Chiang Kai-shek did not take care of Zhang Xueliang, and only later stepped up the custody of Zhang Xueliang, after which Zhang was sent to a military court, Zhang Xueliang was sentenced heavily, but Chiang Kai-shek asked for amnesty for him, and then put him under house arrest, which shows how contradictory Chiang Kai-shek was in this process!
After talking so much, in fact, we can understand why Zhang Xueliang recalled Chiang Kai-shek in his later years and said that Chiang Kai-shek was actually very good to him