The Long March was a military retreat undertaken by the Red Army of the Chinese Communist Party (CCP), the forerunner of the People's Liberation Army, to evade the pursuit of the National Army of the Chinese Nationalist Party (CNP/KMT). However, the most famous began in the Jiangxi (Jiangxi) province in October 1934 and ended in the Shaanxi province in October 1935. The First Front Army of the Chinese Soviet Republic, led by an inexperienced military commission, was on the brink of annihilation by Generalissimo Chiang Kai-shek's troops in their stronghold in Jiangxi province. The CCP, under the eventual command of Mao Zedong and Zhou Enlai, escaped in a circling retreat to the west and north, which reportedly traversed over 9,000 km over 370 days. The route passed through some of the most difficult terrain of western China by traveling west, then north, to Shaanxi.

In October 1935, Mao's army reached Shaanxi province and joined with local Communist forces there, led by Liu Zhidan, Gao Gang, and Xu Haidong, who had already established a Soviet base in northern Shaanxi. The remnants of Zhang's Fourth Red Army eventually rejoined Mao in Shaanxi, but with his army destroyed, Zhang, even as a founding member of the CCP, was never able to challenge Mao's authority. After an expedition of almost a year, the Second Red Army reached Bao'an (Shaanxi) on October 22, 1936, known in China as the "union of the three armies", and the end of the Long March.

All along the way, the Communist Army confiscated property and weapons from local warlords and landlords, while recruiting peasants and the poor. Nevertheless, only some 8,000 troops under Mao's command, the First Front Army, ultimately made it to the final destination of Yan'an in 1935. Of these, less than 7,000 were among the original 100,000 soldiers who had started the march. A variety of factors contributed to the losses including fatigue, hunger and cold, sickness, desertion, and military casualties. During the retreat, membership in the party fell from 300,000 to around 40,000.

In November 1935, shortly after settling in northern Shaanxi, Mao officially took over Zhou Enlai's leading position in the Red Army. Following a major reshuffling of official roles, Mao became the chairman of the Military Commission, with Zhou and Deng Xiaoping as vice-chairmen. (After Zhang Gutao reached Shaanxi, Deng was replaced by Zhang). This marked Mao's position as the pre-eminent leader of the Party, with Zhou in a position second to Mao. Both Mao and Zhou would retain their positions until their deaths, in 1976.

While costly, the Long March gave the CCP the isolation it needed, allowing its army to recuperate and rebuild in the north. It also was vital in helping the CCP to gain a positive reputation among the peasants due to the determination and dedication of the surviving participants of the Long March. In addition, policies ordered by Mao for all soldiers to follow, the Eight Points of Attention, instructed the army to treat peasants respectfully and pay fairly for, rather than confiscate, any goods, in spite of the desperate need for food and supplies. This policy won support for the Communists among the rural peasants.

The Long March solidified Mao's status as the undisputed leader of the CCP, though he did not officially become party chairman until 1943. Other survivors of the March also went on to become prominent party leaders well into the 1990s, including Zhu De, Lin Biao, Liu Shaoqi, Dong Biwu, Ye Jianying, Li Xiannian, Yang Shangkun, Zhou Enlai and Deng Xiaoping.