In 1934 the Zagreb Provincial Committee sent Tito to Vienna where all the Central Committee of the Communist Party of Yugoslavia had sought refuge. He was appointed to the Committee and started to appoint allies to him, among them Edvard Kardelj, Milovan Đilas, Aleksandar Ranković and Boris Kidrič. In 1935, Tito travelled to the Soviet Union, working for a year in the Balkans section of Comintern. He was a member of the Soviet Communist Party and the Soviet secret police (NKVD). Tito was also involved in recruiting for the Dimitrov Battalion, a group of volunteers serving in the Spanish Civil War. In 1936, the Comintern sent "Comrade Walter" (i.e. Tito) back to Yugoslavia to purge the Communist Party there. In 1937, Stalin had the Secretary-General of the CPY, Milan Gorkić, murdered in Moscow. Subsequently Tito was appointed Secretary-General of the still-outlawed CPY.