Radek was arrested after the Spartacist uprising on 12 February 1919 and held in Moabit prison until his release in January 1920. While he was in Moabit, the attitude of the German authorities towards the Bolsheviks changed. The idea of creating an alliance of nations that had suffered from the Versailles treaty — principally Germany, Russia and Turkey — gained currency in Berlin, as a result of which Radek was allowed to receive a stream of visitors in his prison cell, including Walter Rathenau, Arthur Holitscher, Enver Pasha, and Ruth Fischer.On his return to Russia Radek became the Secretary of the Comintern, taking the main responsibility for German issues. He was removed from this position after he supported the KPD in opposing inviting representatives of the Communist Workers' Party of Germany to attend the 2nd Congress of the Comintern, pitting him against the Comintern's executive and the Communist Party of the Soviet Union. It was Radek who took up the slogan of Stuttgart communists of fighting for a United Front with other working class organisations, that later formed the basis for the strategy developed by the Comintern.