After the German–Soviet Non-Aggression Pact and Germany's invasion of Poland of 1939—and despite Thälmann's loyalty to Stalin during his time leading the KPD—Moscow pragmatically removed a slogan for the 1939 International Youth Day which read in part, "Long live Comrade Thälmann!" and replaced it with, "Long live the wise foreign policy of the Soviet Union, guided by Comrade Stalin's instructions." As it turned out, Thälmann's long-time party rival Walter Ulbricht had ignored several requests for help from Thälmann's family when the thawing in German–Soviet relations could have made a release possible, preferring to let Thälmann remain imprisoned. Fellow German Communist, Wilhelm Pieck had managed to escape to the Soviet Union and in July 1936 he issued a statement calling for the release of Thälmann: "If we succeeded in raising a tremendous storm of protest throughout the world, it will be possible to break down the prison walls and as in the case of Dimitrov, deliver Thälmann from the clutches of the Fascist hangmen. The fact that Ernst Thälmann has got to spend his fiftieth birthday in the gaols of Hitler-Fascism is an urgent reminder to all the anti-Fascists of the whole world that they must intensify to the utmost their campaign for the release of Thälmann and the many thousands of imprisoned victims of the White Terror." However, these attempts at raising publicity for his plight were in vain; during the 1930s, numerous German communists who had been close to Thälmann had been murdered in Stalin's camps.