Interwar China was a broken country rife with extreme poverty, lawlessness and political instability, stuck in a tenuous international position. However, it was still a country with millennia of history and a uniformly recognized national and cultural identity that none of its different factions or the various foreign powers denied.
China during the last dynasty
Chinese history stretches back through the ages and disappears in the mists of time long before year, but a possible starting point for China could be the founding of the empire in 221 BCE. Since then, China was ruled by changing dynasties until the 20th century, though there were interregnums during which nobody could establish control over the entire country.
The final dynasty, Qing, was founded by the Manchu people who conquered China from the north in the mid-17th century. In many ways, the Qing Dynasty marked a high point for Chinese power with massive territorial gains during the 18th century. Starting in the late 18th century, the fortunes of the Qing Dynasty waned as a series of weak child emperors took the throne at the same time as the country ran into significant internal turmoil with a number of exceptionally large rebellions as a consequence. Not only did a major economic downturn follow this weakness, impoverishing much of the population, it also opened China to the ambitions of foreign powers. China's weakness coincided with the industrialization in Europe and the US and with the explosive growth in the colonial empires of particularly the UK and France across the planet.
During the 19th century, the UK led a series of successful wars against China in order to establish privileged access to Chinese resources. These privileges were rapidly extended to other western powers and later Japan. The wars didn't just undermine the legitimacy of the Qing Dynasty and drained its resources, they also resulted in the establishment of concessions, parts of China governed by foreign laws, and in a number of Chinese institutions getting adapted along a western pattern. The wars and their accompanying demands contributed to the destitution of China, both through the destruction of Chinese resources, weakening government control and through opening China to direct competition with western industry. Attempts at modernization met with political resistance and failed and following a failed war with Japan and the brutal suppression of the so called Boxer Rebellion in 1900, the Qing Dynasty was definitely broken. It continued for a time, subject to western powers and initiated rapid modernization of the army and the nation as a whole, these were met with serious issues due to a lack of legitimacy and funding.
During the last years of the Qing Dynasty a nationalist, republican opposition grew in the southern province of Guangdong. It evolved into the nationalist party the Guomindang led by Sun Yatsen. On one hand, the party sought to modernize China according to a Japanese pattern and to learn from the western powers, on the other hand it saw the imperial submission to the foreign powers as weakness and a national humiliation. It also had a nativist streak of demanding a China for the Chinese and pointed out that the Qing Dynasty had been founded by Manchu conquerors. The conflict between the imperial government and the Guomindang came to a head a brief civil war that led to the proclamation of the Republic of China and the subsequent abdication of the imperial administration on behalf of the child emperor Puyi in 1912. Following the establishment of the republic, Sun Yatsen transferred power to the most powerful in China, the military chief of staff Yuan Shikai.
Military dictatorship and fragmentation
During Yuan Shikai's four year tenure as president as the construction of a Chinese stat got caught in power struggles between the army and civilian politicians, leading to several rebellions against his perceived dictatorship. Yuan further divided the country by agreeing to a number of Japanese demands about further territorial concessions and Japanese privileges and through his attempt at proclaiming himself emperor. However, Yuan died before these conflicts could topple him. His death left a vacuum of power in China that nobody was capable of filling and China fractured into self-governing territories led by the officers of the local army units, the so called warlords.
Over the next 12 years, these warlords lived in a state of internecine war over valuable targets such as important railway lines, the few industrial centers of China and the capital of Beijing, with shifting alliances, borders and warlords as a consequence. The warlords were a diverse lot with divergent goals. Among the more important were Qing loyalists trying to restore Puyi to the throne, authoritarian nationalists viewing the others as unprincipled rebels, opportunists looking to line their pockets and many more. Common to them was that none were powerful enough to seize power and establish a unified Chinese government.
In the wake of the battle between the warlords and in the territories none of them could fully dominate, central authority crumbled leading to severe lawlessness. How pronounced this phenomenon was varied greatly depending on the strength of the local warlord and the value of a given region. Manchuria was a relative functional, if weak, state for example. This was an exception, though, and the extortion of travelers and locals by military units and gangs of bandits was a widespread phenomenon across China, with further harmful consequences for the population and the economy.
The May 4th Movement, the Guomindang and the Chinese Communist Party
while China's domestic problems grew, the western powers had largely withdrawn from China, concerned with the First World War (1914-1918) and the peace treaty that followed and lacked the resources for active involvement in China. This came to an end in 1919 with the negotiations regarding German possessions in China when Japanese claims to these territories carried the day. This decision and the weakness of the Beijing government's protests against it triggered a surge of anger among the urban, educated elite in China, particularly in Beijing and the free, international city of Shanghai. The protests and the nationalist awakening they brought with them became known as the May 4th movement. This not just led to a general increase in nationalist sentiment, but also to Chinese intellectual circles seeking an answer to the behavior of the great powers in western political theory. The May 4th Movement greatly enhanced the legitimacy and material support for the Guomindang, allowing it to establish its own southern state based in the Guangdong Province.
Another important consequence of the May 4th Movement and the end of WWI was the founding of the Chinese Communist Party in Shanghai in 1921. The party didn't just draw its inspiration from the Soviet Union and the Russian Revolution, it received active Russian support, both economically and in the form of ideological and organizational education and advice. Like the Guomindang the Communists desired a strong, unified China independent of the western powers and Japan and as such it joined the Guomindang as a group, dominating is left wing. This didn't mean that the Communist Party dissolved itself or cut ties with the Soviet Union. Instead it maintained its own, independent organization alongside that of the Guomindang and brought its Russian connections to the larger party.
The Guomindang conquest of China
With Soviet and public support, the Guomindang gradually expanded its control over southern China and spent the first half of the 1920s building an effective army with which to conquer China and suppress the warlords and the chaos they had caused. This army was led by General Chiang Kaishek, who despite having received his military education in Moscow led the right wing of the Guomindang and was the primary opponent of the Communists within the party.
Despite internal tensions between the left and right wings of the party and the death of Sun Yatsen in 1925, the Guomindang preserved its unity and launched its northern expedition to suppress the warlords and reestablish central government in 1926. The basic strategy for the northern expedition was to let the Communists form the vanguard, entering the major cities to mobilize the workers to general strike. When the strike struck and the ability of the local warlord to control and fortify the city had been paralyzed, the Guomindang army would strike and take control of the city, gradually driving the warlords back.
The strategy worked and the Guomindang rapidly advanced through southern China throughout 1926, among others conquering Wuhan, the second most important industrial center in China and the city dominating traffic on the Yangtze, establishing its new capital there. In addition, a number of southern warlords swore loyalty to the Guomindang, adding their troops to its.
The unity of the Guomindang shatters
In spring 1927, the advance had reached the Chinese districts of Shanghai. The Communists started a general strike, the local warlord was driven back and half of China was in Guomindang hands. This put the party in a sufficient position of power for that Chiang Kaishek judged the time right to break the unity of the Guomindang and purge the Communists from the party. In an alliance with the gangster organization known as the Green Gang and the white lords of Shanghai, the leadership of the Communists and the unions in Shanghai was massacred in the span of a single night.
Following this, Chiang declared his own government in Nanjing with the support of China's wealthiest families. With the entire northern expedition at stake, the Wuhan government capitulated and ordered the purge of the Communists from the party. Following brief skirmishes near Wuhan, the Communists were banished from the Guomindang, eliminated as an important player in Chinese politics and the survivors banished to a few remote, mountainous regions. With the chaos in Wuhan, Chiang's Nanjing government maintained a clear dominance over the Wuhan government and his coup succeeded.
Under the sole leadership of Chiang, the northern expedition was resumed. He conquered Beijing in 1928 and most of the remaining warlords submitted to Chiang as the legitimate president of China.
The Republic of China
Despite the political unification of China and the support of its richest citizens, the issue of extreme poverty was far from resolved, just like corruption in the administration remained a severe problem for the Republic of China. This meant that the government finances were never truly reigned in and people who could afford it hid their money abroad rather than invest them in the Chinese economy.
In addition, the Guomindang victory had not brought an end to political instability. The majority of the warlords had submitted to the Guomindang, bu they still maintained their own, local power bases and military units. Not just that, a number of new warlords had risen from the chaos of the northern expedition. These warlords kept warring against each other, with the single greatest warlords happening following the northern expedition. Finally, Chiang still viewed the Communists as a threat to his government and the continued unity of China and expended great resources fighting its remnants.
Foreign interest in China had not been significantly weakened either. The western powers maintained their concessions and economic privileges. More importantly, Japanese aggression kept mounting. In 1931 Japan annexed Manchuria under a pretext of protecting its railway interests, leading to a brief war in 1932. During the 1930s it became increasingly obvious to most, though not to Chiang, that Japan wouldn't be satisfied merely with Manchuria.
The Second World War and the Chinese Civil War
The inevitable Japanese invasion happened in 1937 and in a few months all of eastern China was in Japanese hands. The Guomindang government was forced to abandon Nanjing and reestablish itself in the utmost west of China and despite a decade of hostility, the Guomindang, the Chinese Communist Party and the remaining warlords allied against the Japanese invasion. Despite the Japanese invasion, the groups largely operated independently and battles between the Guomindang and Communist forces continued.
The war in China became part of a larger war with the outbreak of the Second World War in 1939, leading to military support from the US, and to a lesser degree the UK and the Soviet Union. Despite this support and the pressure the Japanese came on due to the American forces in the Pacific, the Guomindang kept losing ground to the Japanese army as the war went on. The Communists on the other hand were able to seize control of large territories in northern China.
Immediately after the end of WWII fighting resumed between a weakened Guomindang and a resurgent Communist Party. The Chinese civil war ended in 1949 with a Communist victory, ending territorial concessions to foreign powers and unifying almost all of China for the first time in decades. The exceptions were Taiwan, the last base of the Guomindang where Chiang Kaishek maintained an independent government, the British crown colony of Hong Kong and the small Portuguese colony of Macau.