Sun Yat-sen died of cancer in Beijing in March 1925, but the Nationalist movement he had helped to initiate was gaining momentum. During the summer of 1925, Chiang, as commander-in-chief of the National Revolutionary Army, set out on the long-delayed Northern Expedition against the northern warlords. Within nine months, half of China had been conquered. By 1926, however, the Guomindang had divided into left- and right-wing factions, and the Communist bloc within it was also growing. In March 1926, after thwarting a kidnapping attempt against him, Chiang abruptly dismissed his Soviet advisers, imposed restrictions on CCP members' participation in the top leadership, and emerged as the preeminent Guomindang leader. The Soviet Union, still hoping to prevent a split between Chiang and the CCP, ordered Communist underground activities to facilitate the Northern Expedition, which was finally launched by Chiang from Guangzhou in July 1926.
In early 1927 the Guomindang-CCP rivalry led to a split in the revolutionary ranks. The CCP and the left wing of the Guomindang had decided to move the seat of the Nationalist government from Guangzhou to Wuhan. But Chiang, whose Northern Expedition was proving successful, set his forces to destroying the Shanghai CCP apparatus and established an anti-Communist government at Nanjing in April 1927. There now were three capitals in China: the internationally recognized warlord regime in Beijing; the Communist and left-wing Guomindang regime at Wuhan; and the right-wing civilian-military regime at Nanjing, which would remain the Nationalist capital for the next decade...
But in mid-1927 the CCP was at a low ebb. The Communists had been expelled from Wuhan by their left-wing Guomindang allies, who in turn were toppled by a military regime. By 1928 all of China was at least nominally under Chiang's control, and the Nanjing government received prompt international recognition as the sole legitimate government of China. The Nationalist government announced that in conformity with Sun Yat-sen's formula for the three stages of revolution--military unification, political tutelage, and constitutional democracy--China had reached the end of the first phase and would embark on the second, which would be under Guomindang direction.
...stepped-up military aggression abroad. A prelude to this state of affairs was Tanaka Giichi's term as prime minister from 1927 to 1929. Twice he sent troops to China to obstruct Chiang Kai-shek's unification campaign.