The majority of the people in China had lost interest in which party was in control since they considered the Japanese to be of much greater concern. The sentiment against internal strife had been growing since the Japanese had invaded in 1931. By 1936, even the CCP and KMT finally decided that their greatest enemy was not the other party but the invading outsiders who continued to chip away at Chinese territories. Though this sentiment was growing within both parties, the leaders did not seem quite as understanding. It took one of the KMT officers abducting the KMT leader, Chiang Kai-shek, to finally force the leaders of the parties to work together to remove the growing Japanese threat. Known as the Xi'an Incident, it was only resolved when the KMT and CCP finally formed a tense alliance, which was called the Second United Front.

Prior to the incident, Chiang Kai-shek followed a strategy of "first internal pacification, then external resistance" that entailed eliminating the CCP and appeasing Japan to allow time for the modernization of China and its military. After the incident, Chiang aligned with the Communists against the Japanese. However, by the time Chiang arrived in Xi'an on 4 December 1936, negotiations for a united front had been in the works for two years. The crisis ended after two weeks of negotiation, in which Chiang was eventually released and returned to Nanjing, accompanied by Zhang Xueliang. Chiang agreed to end the ongoing civil war against the CCP and began actively preparing for the impending war with Japan.