Wu returned to China in May 1931, when the Communist movement was at its nadir.[1] He enlisted in the Red Army and participated in the Long March.[2] At the crucial Zunyi Conference in 1935, Wu served as the interpreter for the Comintern advisor Otto Braun (Li De), but opposed Braun and supported Mao Zedong's strategy, unlike other returnees from the Soviet Union who supported Comintern's orthodox line.[3]