Back in 1875 he had been a delegate at the congress in Gotha which had agreed the unification of the General German Workers' Association ("Allgemeiner Deutscher Arbeiter-Verein" / ADAV) and the Social Democratic Workers' Party ("Sozialdemokratische Arbeiterpartei Deutschlands" / SDAP), paving the way for the creation of the unified Social Democratic Party.
In 1919 she joined the Young Free Socialists ("Freie sozialistische Jugend") and in 1923 the recently launched Communist Party of Germany.
[2] Meanwhile, in 1919 she had married the architect, originally from Stuttgart, Richard Daniel, a man who co-founded the local (Ulm) branch of the Communist Party at the end of 1919.
[2][6] Berta Daniel was, from its beginning, a member of the "Anti-Militarist Structure" ("AM-Apparat"), an illegal Communist Party intelligence service which existed in Germany till 1937.
[5] Berta Daniel was released after her father provided a guarantee on her behalf, and "went underground", living illegally (i.e. unregistered) in Berlin and other cities, while their daughter stayed with their father until he was arrested because of his own activities, after which she was sent to a children's home run by International Red Aid ("Internationale Rote Hilfe" / "Международная организация помощи борцам революции" IRH/МОПР), a Soviet sponsored workers' welfare operation.
[2] Comrades with whom she worked in the IRH included Lenin's former assistant, Elena Stasova, and her fellow "AM-Apparat" member, Eugen Schönhaar.
[1] The Soviet capital was by now the scene of a major and sustained purge of actual and presumed enemies of the leadership, with intelligence workers and foreigners particularly vulnerable to denunciation.
[2] Richard Daniel, who worked in Moscow as a building engineer, would be arrested in February 1938 and die in a labour camp at Kotlas in June 1942.
[1][7] She was released in Tayshet at the end of 1952 after spending 15 years and 9 months in a succession of labour camps and other centres of detention between Moscow and Vladivostok.
[1] One member of the intelligence community who had not fallen foul of the Stalin purges was Elena Stasova, with whom Daniel had worked at the IRH in the 1920s.
[5] It appears that it was as a result of their ensuing communication that on 28 January 1957 Richard Daniel was posthumously rehabilitated by the appropriate Moscow military tribunal.