The republic that Sun Yat-sen and his associates envisioned evolved slowly. The revolutionists lacked an army, and the power of Yuan Shikai began to outstrip that of parliament. Yuan revised the constitution at will and became dictatorial. In August 1912 a new political party was founded by Song Jiaoren (1882-1913), one of Sun's associates.

In November Yuan Shikai, legally president, ordered the Guomindang dissolved and its members removed from parliament. Within a few months, he suspended parliament and the provincial assemblies and forced the promulgation of a new constitution, which, in effect, made him president for life. Yuan's ambitions still were not satisfied, and, by the end of 1915, it was announced that he would reestablish the monarchy. Widespread rebellions ensued, and numerous provinces declared independence. With opposition at every quarter and the nation breaking up into warlord factions, Yuan Shikai died of natural causes in June 1916, deserted by his lieutenants.

After Yuan Shikai's death, shifting alliances of regional warlords fought for control of the Beijing government. The nation also was threatened from without by the Japanese. When World War I broke out in 1914, Japan fought on the Allied side and seized German holdings in Shandong Province.

In 1917 China declared war on Germany in the hope of recovering its lost province, then under Japanese control. But in 1918 the Beijing government signed a secret deal with Japan accepting the latter's claim to Shandong. When the Paris peace conference of 1919 confirmed the Japanese claim to Shandong and Beijing's sellout became public, internal reaction was shattering. On May 4, 1919, there were massive student demonstrations against the Beijing government and Japan. The political fervor, student activism, and iconoclastic and reformist intellectual currents set in motion by the patriotic student protest developed into a national awakening known as the May Fourth Movement. The intellectual milieu in which the May Fourth Movement developed was known as the New Culture Movement and occupied the period from 1917 to 1923. The student demonstrations of May 4, 1919 were the high point of the New Culture Movement, and the terms are often used synonymously. Students returned from abroad advocating social and political theories ranging from complete Westernization of China to the socialism that one day would be adopted by China's communist rulers.

The May Fourth Movement helped to rekindle the then-fading cause of republican revolution. In 1917 Sun Yat-sen had become commander-in-chief of a rival military government in Guangzhou in collaboration with southern warlords. In October 1919 Sun reestablished the Guomindang to counter the government in Beijing.

The CCP was still small at the time, having a membership of 300 in 1922 and only 1,500 by 1925. The Guomindang in 1922 already had 150,000 members. Soviet advisers also helped the Nationalists set up a political institute to train propagandists in mass mobilization techniques and in 1923 sent Chiang Kai-shek (Jiang Jieshi), one of Sun's lieutenants from Tongmeng Hui days, for several months' military and political study in Moscow. After Chiang's return in late 1923, he participated in the establishment of the Whampoa (Huangpu) Military Academy outside Guangzhou, which was the seat of government under the Guomindang-CCP alliance. In 1924 Chiang became head of the academy and began the rise to prominence that would make him Sun's successor as head of the Guomindang and the unifier of all China under the right-wing nationalist government.

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 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.

The Comintern cause appeared bankrupt. A new policy was instituted calling on the CCP to foment armed insurrections in both urban and rural areas in preparation for an expected rising tide of revolution. Unsuccessful attempts were made by Communists to take cities such as Nanchang, Changsha, Shantou, and Guangzhou, and an armed rural insurrection, known as the Autumn Harvest Uprising, was staged by peasants in Hunan Province. The insurrection was led by Mao Zedong (1893-1976), who would later become chairman of the CCP and head of state of the People's Republic of China. Mao was of peasant origins and was one of the founders of the CCP.

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 decade of 1928-37 was one of consolidation and accomplishment by the Guomindang. Some of the harsh aspects of foreign concessions and privileges in China were moderated through diplomacy.There were forces at work during this period of progress that would eventually undermine the Chiang Kai-shek government. The first was the gradual rise of the Communists. Mao Zedong, who had become a Marxist at the time of the emergence of the May Fourth Movement (he was working as a librarian at Beijing University), had boundless faith in the revolutionary potential of the peasantry.

Mao's prestige rose steadily after the failure of the Comintern-directed urban insurrections.

In the early 1930s, amid continued Political Bureau opposition to his military and agrarian policies and the deadly annihilation campaigns being waged against the Red Army by Chiang Kai-shek's forces, Mao's control of the Chinese Communist movement increased. The epic Long March of his Red Army and its supporters, which began in October 1934, would ensure his place in history.

Few Chinese had any illusions about Japanese designs on China. Hungry for raw materials and pressed by a growing population, Japan initiated the seizure of Manchuria in September 1931 and established ex-Qing emperor Puyi as head of the puppet regime of Manchukuo in 1932.

The Chinese resistance stiffened after July 7, 1937, when a clash occurred between Chinese and Japanese troops outside Beijing (then renamed Beiping) near the Marco Polo Bridge.

At Yan'an and elsewhere in the "liberated areas," Mao was able to adapt Marxism-Leninism to Chinese conditions. He taught party cadres to lead the masses by living and working with them, eating their food, and thinking their thoughts.

In 1945 China emerged from the war nominally a great military power but actually a nation economically prostrate and on the verge of all-out civil war.

During World War II, the United States emerged as a major actor in Chinese affairs. As an ally it embarked in late 1941 on a program of massive military and financial aid to the hard-pressed Nationalist government.

The wartime policy of the United States was initially to help China become a strong ally and a stabilizing force in postwar East Asia.

Through the mediatory influence of the United States a military truce was arranged in January 1946, but battles between Nationalists and Communists soon resumed.

Belatedly, the Nationalist government sought to enlist popular support through internal reforms. The effort was in vain, however, because of the rampant corruption in government and the accompanying political and economic chaos.

In January 1949 Beiping was taken by the Communists without a fight, and its name changed back to Beijing. Between April and November, major cities passed from Guomindang to Communist control with minimal resistance. In most cases the surrounding countryside and small towns had come under Communist influence long before the cities. After Chiang Kai-shek and a few hundred thousand Nationalist troops fled from the mainland to the island of Taiwan, there remained only isolated pockets of resistance. In December 1949 Chiang proclaimed Taipei, Taiwan, the temporary capital of China.