Yuan Shikai was in charge of the Beiyang Army, the military of northern China. He was promised the position of President of the Republic of China if he could get the Qing court to abdicate.New Army that had mutinied was limited and there were still significant forces which still had not declared against the Qing.
On 12 February 1912 Emperor Puyi did abdicate the throne. Sun Yat-sen stepped down as President, and Yuan became the new provisional president in Beijing on 10 March 1912. The provisional government did not have any military forces of its own, its control over elements of the
Sun Yat-sen sent telegrams to the leaders of all provinces, requesting them to elect and to establish the National Assembly of the Republic of China in 1912. In May 1912 the legislative assembly moved from Nanjing to Beijing with its 120 members divided between members of Tongmenghui and a Republican party that supported Yuan Shikai. Many revolutionary members were already alarmed by Yuan's ambitions and the northern based Beiyang government..
Tongmenghui member Song Jiaoren quickly tried to control the parliament. He mobilized the old Tungmenghui at the core with the merger of a number of new small parties to form a new political party called the Guomindang (Chinese nationalist party) on 25 August 1912 at Huguang Guild Hall Beijing. The 1912–1913 National assembly election was considered a huge success for the KMT winning 269 of the 596 seats in the lower house and 123 of the 274 senate seats. The Second Revolution took place where Sun and KMT military forces tried to overthrow Yuan's forces of about 80,000 men in an armed conflict in July 1913. The revolt against Yuan was unsuccessful. Sun was forced to seek asylum in Japan. In retaliation the national party leader Song Jiaoren was assassinated, almost certainly by a secret order of Yuan, on 20 March 1913.
In 1915 Yuan Shikai proclaimed the Empire of China (1915–1916) with himself as Emperor of China. Sun took part in the Anti-Monarchy war of the Constitutional Protection Movement, while also supporting bandit leaders like Bai Lang during the Bai Lang Rebellion. This marked the beginning of the Warlord Era. In 1915 Sun wrote to the Second International, an socialist-based organization in Paris, asking it to send a team of specialists to help China set up the world's first socialist republic. At the time there were many theories and proposals of what China could be. In the political mess, even when Sun Yat-sen was announced as President, Xu Shichang was also announced as President of the Republic of China.
China had become divided between different military leaders without a proper central government. Sun saw the danger of this and returned to China in 1917 to advocate Chinese reunification. In 1921 he started a self-proclaimed military government in Guangzhou and was elected Grand Marshal. Between 1912 and 1927 three governments had been set up in South China: the Provisional government in Nanjing (1912), the Military government in Guangzhou (1921–1925), and the National government in Guangzhou and later Wuhan (1925–1927). The southern separatist government in the South was established to rival the Beiyang government in the north. Yuan Shikai had banned the KMT. The short lived Chinese Revolutionary Party was a temporary replacement for the KMT. On 10 October 1919 Sun resurrected the KMT with the new name Chung-kuo Kuomintang, basically "Chinese Nationalist party".
KMT CPC cooperationBy this time Sun had become convinced that the only hope for a unified China lay in a military conquest from his base in the south, followed by a period of political tutelage that would culminate in the transition to democracy. In order to hasten the conquest of China, he began a policy of active cooperation with the Communist Party of China (CPC). Sun and the Soviet Union's Adolph Joffe signed the Sun-Joffe Manifesto in January 1923. Sun received help from the Comintern for his acceptance of communist members into his KMT. Revolutionary and socialist leader Vladimir Lenin praised Sun and the KMT for their ideology and principles. Lenin praised Sun and his attempts at social reformation, and also congratulated him for fighting foreign Imperialism. Sun also returned the praise, calling him a "great man", and sent his congratulations on the revolution in Russia.
With the Soviets' help, Sun was able to develop the military power needed for the Northern Expedition against the military at the north. He established the Whampoa Military Academy near Guangzhou with Chiang Kai-shek as the commandant of the National Revolutionary Army (NRA). Other Whampoa leaders include Wang Jingwei and Hu Hanmin as political instructors. This full collaboration was called the First United Front.
In 1924 Sun appointed TV Soong to set up the first Chinese Central bank called the Canton Central Bank. To establish national capitalism and a banking system was a major objective for the KMT. However Sun was not without some opposition as there was the Canton volunteers corps uprising against him
In February 1923 Sun made a presentation to the Students' Union in Hong Kong University and declared that it was the corruption of China and the peace, order and good government of Hong Kong that turned him into a revolutionary.This same year, he delivered a speech in which he proclaimed his Three Principles of the People as the foundation of the country and the Five-Yuan Constitution as the guideline for the political system and bureaucracy. Part of the speech was made into the National Anthem of the Republic of China.
On 10 November 1924, Sun traveled north to Tianjin and delivered a speech to suggest a gathering for a "National conference" for the Chinese people. It called for the end of warlord rules and the abolition of all unequal treaties with the Western powers. Two days later, he traveled to Beijing to discuss the future of the country, despite his deteriorating health and the ongoing civil war of the warlords. Among the people he met the Muslim General Ma Fuxiang, who informed Sun that they would welcome the leadership of Dr. Sun. On 28 November 1924 Sun traveled to Japan and gave a speech on Pan-Asianism at Kobe, Japan.
Sun died of liver cancer on 12 March 1925 at the age of 58 at the Rockefeller financed Peking Union Medical College. In keeping with common Chinese practice, his remains were placed in the Temple of Azure Clouds, a Buddhist shrine in the Western Hills a few miles outside of Beijing.
A mausoleum was built and completed in 1929. On 1 June 1929, Sun's remains were relocated from Beijing and buried in Sun Yat-sen Mausoleum in Nanjing