With a new alliance, the two parties (CPC and KMT) made Guangdong province their revolutionary base, and prepared for Northern Expedition, which would sweep away the rule of the warlords, break the military and political control of imperilist countries over China and end tribulation.

In 1925, the KMT formed Guangdong National Government in the Northern Expedition. In order to drum up support for Northern Expedition, the CPC did active publicy and organizational work among workers and farmers, establishing a broad and firm base among the masses for Northern Expedition.

In July 1926, National Revolution Army set off on its northward march, marking the beginning of Northern Expedition. Northern Expeditionary Army first captured Changsha, the capital of Hunan province, and then pressed on toward Wuhan, which was heavily fortified. The prominent Independent Regiment, which was composed mainly of Communists and commanded by Ye Ting, fought courageously, and won for the Fourth Corps the title of "Iron Army". Northern Expeditionary Army broke through the enemy's line of defense, crossed Yangtze River and occupied Wuhan. In the middle of March 1927, Zhou Enlai led the workers of Shanghai in an armed uprising, ensuring the smooth entry of Northern Expeditionary Army into Shanghai. At the end of March, the army also occupied Nanjing.

Northern Expedition was warmly welcomed and supported by people all over China. In less than ten months, it crushed the main forces of the major warlords Wu Peifu and Sun Chuanfang, and occupied most of the area south of Yangtze River, all struck a heavy blow at the reactionary warlords and kindled the flame of revolution over half of China.