Mao Zedong ( 毛泽东 ) was the chairman of the Communist Party of China from 1943 and the chairman of the Central Committee of the Communist Party of China from 1945 until his death. Under his leadership, the CCP became the ruling party of mainland China . On October 1, 1949, Mao declared the formation of the People's Republic of China ( 中华人民共和国 ) at Tiananmen ( 天安门 ) Square.

As the eldest son of four children of a moderately prosperous peasant farmer, Mao Zedong was born in the village of Shaoshan ( 韶山 ) in Xiangtan county ( 湘潭县 ), Hunan province.

Mao served in the Hunan provincial army during the 1911 Revolution. After graduation from Hunan Normal School in 1918, Mao worked for the Peking University library as an assistant librarian. Instead of going abroad which was the path of many of his radical compatriots, Mao spent the early 1920s traveling in China , and finally returned to Hunan , where he took the lead in promoting collective action and labor rights. At age 27, Mao attended the First Congress of the Communist Party of China in Shanghai in July 1921. Two years later he was elected to the Central Committee of the party at the Third Congress.

During this time, he developed many of his political theories. Mao's thought transformed traditional Marxism into a political ideology that could work to win a revolution and consolidate power in China . Mao hypothesized that peasants could form the basis of a communist revolution. This meant a process of getting party cadres to understand local realities and trying to integrate the concerns of peasants with party policy, something called Mass Line. Mao also developed more practical ideas, such as a three-stage theory of guerilla warfare ( 游击战 ) and the concept of the people's democratic dictatorship.

Mao escaped the white terror in the spring and summer of 1927 and led the ill-fated Autumn Harvest Uprising ( 秋收起义 ) at Changsha, Hunan. Mao, with the help of Zhu De ( 朱德 ) , built a modest but effective guerilla army, undertook experiments in rural reform and government, and provided refuge for Communists fleeing the rightist purges in the cities. Under increasing pressure from the KMT encirclement campaigns, there was a struggle for power within the Communist leadership. Just at that time, Mao was removed from his important positions. To evade the KMT forces, the Communists engaged in the "Long March" ( 长征 ) , a retreat from Jiangxi in the southeast to Shanxi in the northwest of China.

From his base in Yan'an ( 延安 ) , Mao led the Communist resistance against the Japanese in the Sino-Japanese War (1937-1945). During this War, Mao Zedong's strategies were opposed by both Chiang Kai-shek ( 蒋介石 ) and the United States. After the end of World War II, the US continued to support Chiang Kai-shek, now openly against the communist Red Army ( 红军 ) led by Mao Zedong in the civil war for control of China as part of its view to contain and defeat "world communism". On January 21, 1949, Kuomintang forces suffered massive losses against Mao's Red Army. In the early morning of December 10, 1949, Red Army troops laid siege to Chengdu , the last KMT-occupied city in mainland China , and Chiang Kai-shek evacuated to Taiwan on the same day.

After the Japanese were defeated in World War II, the Communists defeated the Kuomintang in an ensuing civil war and established the People's Republic of China on October 1, 1949. From 1954 to 1959, Mao was the Chairman of the PRC. Following the consolidation of power, Mao launched a phase of rapid collectivization, lasting until around 1958. During this period, China sustained yearly increases in GDP of about 4–9% as well as dramatic improvements in quality-of-life indicators such as life expectancy and literacy.

In 1958, Mao launched the Great Leap Forward ( 大跃进 ) , which was lasting about two years, a plan intended as an alternative model for economic growth which contradicted the Soviet model of heavy industry that was advocated by others in the party.

Facing the fact of not being heard on the political stage, Mao responded to Liu and Deng by launching the Cultural Revolution ( 文化大革命 ) in 1966, in which the Communist hierarchy was circumvented by giving power directly to the Red Guards ( 红卫兵 ) , groups of young people, often teenagers, who set up their own tribunals. The Revolution led to the destruction of much of China 's cultural heritage and the imprisonment of a huge number of Chinese intellectuals, amongst other social chaos. In 1969, Mao declared the Cultural Revolution to be over, although the official history of the People's Republic of China marks the end of the Cultural Revolution in 1976 with Mao's death.

In the last years of his life, Mao was faced with declining health due to either Parkinson's disease, as well as lung ailments due to smoking, and heart trouble. As anticipated after Mao's death on September 9, 1976 , there was a power struggle for control of China . On one side were the leftists led by the Gang of Four ( 四人帮 ) , who wanted to continue the policy of revolutionary mass mobilization. On the other side were the rightists, which consisted of two groups. One was the restorationists led by Hua Guofeng ( 华国峰 ) who advocated a return to central planning along the Soviet model. The other was the reformers, led by Deng Xiaoping ( 邓小平 ) , who wanted to overhaul the Chinese economy based on pragmatic policies and to de-emphasize the role of ideology in determining economic and political policy.