Chiang Kai-shek came into contact with revolutionary figures when he studied in Japan in 1906. It was in Tokyo where he met Chen Chi-mei who introduced him to Sun Yat-sen. Two years later he was selected by the Qing Court as an army cadet to study in Japan and it was on his second stay in the country that Chiang joined the Tongmenghui. Initially, he was under the supervision of Chen Chi-mei but during the 1911 Revolution his involvement in the Hangzhou uprising and his success on the battlefield as commander of the 5th Regiment under the 5th Shanghai Army boosted his reputation. Sun Yat-sen later concluded that the revolution failed because the revolutionary party did not possess its own armed forces and decided that the primary focus going forward should be to cultivate a revolutionary army. Ultimately, Sun came to place his hopes for such a vanguard on the shoulders of Chiang Kai-shek, whom he appointed first commandant of Whampoa Military Academy, a post that gave Chiang the opportunity to apply his military training, and also provided him with an important foundation on which to build a career in politics.
However, when Sun Yat-sen died on March 12, 1925, Chiang Kai-shek was still not part of the central leadership of the Kuomintang (KMT). At that time, the Chinese Communist Party had developed its own organization within the KMT and National Revolutionary Army, and the contradictions within the party gradually intensified. After the Zhongshan Warship Incident (the SS Yongfeng had been renamed the SS Zhongshan in 1925), Chiang declared the incident to be part of a communist plot, introduced martial law and forced Wang Chao-ming (Wang Jingwei) to leave Guangzhou for France. As a result of the incident and his response to it, Chiang became commander-in-chief of the National Revolutionary Army and launched a new front in the revolutionary struggle - the Northern Expedition.