 Complete the following phrase:  He first belonged to the left wing of the KPD, led by Ruth Fischer. In 1923, he aligned himself with Arthur Ewert and Gerhart Eisler and became the political leader of the partys Mecklenburg district. He participated in the Hamburg Uprising and in 1924, had to flee to Vienna, from where he was expelled to the Soviet Union in 1925. There, he succeeded Ivan Katz as Communist Party representative to the Comintern. From July to December 1927, he represented the Comintern in China. Working with Georgian communist Vissarion Lominadze, he helped Chinese communists to organize the 