In the same year, he joined the Communist Youth League of China and following the White Terror in 1927, he enrolled himself to the Moscow Sun Yat-sen University in December.

In November, Zhang Gutao got Chen appointed Political Commissar of The Red Fourth Army and together they conducted a major purge.

On 12 October 1932, Chen and Zhang's Red Fourth Army was forced to leave the Eyuwan Soviet due to a series of military defeats.

[6][13][16] In 1935, Chen was tasked to lead the Red Fourth Army on the Long March, and was to rendezvous in July at Xiaojin County, Sichuan.

[6][16] After the failure to implement the "Ningxia Plan", Chen was appointed as Chairman of the Military Committee of the West Army,[17] to lead an attempt with Xu Xiangqian to open a passage to the USSR.

However, after a 4-month battle against the Ma Clique in the Hexi Corridor and facing lack of reinforcements, the West Army was crushed.

Chen was able to escape under the cover of wounded of the defeated West Army, and returned safely to Yan'an on 16 March 1937.