October 1934, the Yudu river in Jiangxi. Some 86,000 Red Army soldiers and porters cross at night, carrying the party's printing presses. By the Xiang river in December half are gone. At Zunyi in January the leaders blame their Comintern adviser, and Mao is back in the leadership.
Why then
Chiang turned on the Communists in 1927. In the hills of Jiangxi, Mao and Zhu De built a peasant army and in 1931 a Soviet republic. Four encirclement campaigns failed; the fifth, planned with German advisers, ringed the base with blockhouses.
What they wanted
Chiang means to finish the Communists before he turns to Japan, and to bring the southwest under his armies on the way. The Communists need a base he cannot reach, and look for one all the way to the northwest.
What changed
About 8,000 of those who left Jiangxi reach Shaanxi in October 1935. In 1936 Chiang's own generals force him into a truce with them against Japan. The survivors will run China after 1949, and the march becomes their founding story.
Still argued
Party histories tell a planned march north to fight Japan; Sun Shuyun, who found the last survivors, tells a flight, past a Luding bridge barely defended. Ed Jocelyn and Andrew McEwen walked it in 2002–03 and measured half the legend's distance. How fast Zunyi made Mao the leader is argued too.