Warmatrix

The 22 years long Chinese Civil War elevated China out of a long period of anarchy, securing it for its communist party.
Starting in the 18th century CE, the industrial revolution made Europe economically and militarily dominant. The Qing dynasty, which ruled China from 1644 CE, was unable to keep up in the geopolitical race and lost more and more influence to foreign powers. In 1912 CE the Chinese empire collapsed, plunging China into a period of anarchy, dominated by local warlords. After a decade, the nationalist Kuomintang party arose and started to re-unify the country again. However there was another contender for power: the Chinese Communist Party. At first these two co-operated, but in 1927 CE ideological differences made them fall out with each other and start a civil war.
At first the Kuomintang had the upper hand, driving the communists from their power base in Wuhan, though others rose up in the south. The nationalists launched several large encirclement campaigns to wipe out the enemy, without success. In 1931 CE, the third campaign was interrupted by the Mukden Incident, staged by the Japanese army. In the preceding decades Japan had industrialized much faster than China and was correspondingly more powerful. The Japanese army used the incident as a pretext to invade and annex Manchuria. When it did not press beyond that region, the Kuomintang leader Chiang Kai-shek made the nationalists resume their attacks on the communists two years later. A fourth campaign eliminated them from several regions; the fifth in 1934 CE squeezed them so hard that they were compelled to break out and flee to the barren Shaanxi province in western China. On the way they lost 90% of their manpower, though the effort was later proclaimed as a feat of heroism, called the 'Long March'. During this time Mao Zedong rose to a position of absolute leader of the communists. They began to call for a united front against the Japanese, though in reality shied away from fighting against them. Nonetheless the propaganda fractured the ranks of the Kuomintang. When Chiang Kai-shek tried to restore order, he was briefly imprisoned.
In 1937 CE Japan started the Second Sino-Japanese War, conquering most of east China. This interrupted the civil war again, on a larger scale than before. The Kuomintang and the communists grudgingly instituted a mutual ceasefire and engaged the Japanese. Yet they also continued to compete with each other, creating a complex three-sided war. After a few defeats the two Chinese parties realized that the Japanese forces were superior, though also that the war would not last forever, so they both sat down to wait it out. Because of its position the Kuomintang suffered the main Japanese attacks, but had too much territory and manpower to be defeated completely. In the meanwhile the communists strengthened their organization and army, won support in the countryside and conducted mostly small guerrilla attacks on the Japanese garrisons.
During and after the world war the Kuomintang received support from the USA; the communists from the USSR. In 1945 CE the Russian Red Army pushed the Japanese out of Manchuria. The subsequent surrender of Japan in World War II ended the foreign occupation in other parts of China also. For more than a year, the Kuomintang and communists raced to gain as much territory and influence as possible. With a little help from the USSR, the latter obtained a substantial amount of weapons from disbanding Japanese units. The communists ended up dominating northwestern China; the nationalists the center and south.
In late 1945 CE the two parties signed a peace agreement, but it broke down within months. Again the Kuomintang gained the upper hand, even capturing the communist base in Shaanxi in 1947 CE. However by then the latter were already firmly established in the countryside in large parts of China. By the end of that year, approximately 2.7 million nationalists were facing 1.2 million communists, though the former were spread thin over a large area and forced into a defensive stance. The quality of the nationalist troops varied strongly.
Much of the active fighting took place in Manchuria, which was rich in industrial resources. At first the communists tried to wear out the Kuomintang with reasonable success, while they gradually transformed from a guerrilla force to a regular army. The Kuomintang secured much territory yet gained little by it, while becoming overextended in the process. In the summer of 1947 CE the communists took to the offensive, aiming for the nationalist lines of communication. They gained full control over the countryside, while the Kuomintang held on to the cities. In 1948 CE the tide turned. The communists launched their decisive Liaoshen campaign, which targeted the cities. At first the balance swung back and forth, then one city after another fell and Manchuria was secured. During the subsequent Huaihai campaign they surrounded the enemy and effectively starved them out. In the Pingjin campaign they secured control of Beiping, which was renamed to Beijing, and with it the North China Plain.
By 1949 CE the Kuomintang was effectively beaten, though still had a massive army and ruled more than half of China. But their cohesion was weak. When the communists advanced into the south, the capitalists broke and and retreated to Taiwan, establishing the Republic of China, while the mainland became the People's Republic of China. Up to this day both claim sovereignty over the whole of China and co-exist in a state or armed peace.
Throughout almost the entire war the Kuomintang had superior numbers, resources and weaponry. Despite that they lost, because of the disruptive effects of the Japanese invasions and also internal fractionalism, corruption and incoherent strategy. The communists won because they were better organized and built up their strength from a small nucleus, until they were strong enough to claim victory.