Moritz Thalheimer, her father, was a prosperous businessman and real estate agent with an active interest in politics.
They gravitated easily to the left of the party working on political matters with friends such as Rosa Luxemburg, Clara Zetkin, Fritz Westmeyer and the Mehrings.
An antiwar group quickly emerged in the Württemberg SPD with Clara Zetkin, Fritz Westmeyer and the Thalheimer siblings at its heart.
[1] In 1915 Bertha Thalheimer was a co-founder of the anti-war Spartacus League,[2] and was one of the organisers of its launch conference held in Berlin in January 1916.
[1] Although the anti-war message gained popular traction, the political authorities in the leading belligerent powers - except in the Russian Empire - were untouched by it: in March 1917 Thalheimer, who had been participating in anti-war street protests in defiance of court orders,[5] was arrested for "anti-military activities" (wegen "antimilitaristischer Tätigkeit"): in October 1917 she was convicted on charges of high treason by a Stuttgart court, which sentenced her to two years in prison.
[1] While her brother, for a couple of years during the early 1920s, took a leading position in the party, Bertha Thalheimer was a co-founder in 1925, of the Red Women's and Girls' League ("Der „Rote Frauen und Mädchenbund“" / RFMB).
[1][3][2] Bertha Thalheimer worked for the KPO as a speaker and as a journalist, writing contributions for the party's bimonthly newspaper "Arbeiterpolitik"[6] and for the Stuttgart-based "Arbeiter-Tribüne".
The political backdrop changed, as it seemed, permanently in January 1933 when the Nazi Party took power in Germany and lost little time in transforming the country into a one-party dictatorship.
This was the context in which Karl Wilhelm Schöttle, who was categorised as an Aryan, and Bertha Thalheimer were now divorced, although she continued to receive material support from her former husband.
[5] After she was liberated by the Soviet army in May 1945, Bertha Thalheimer immediately returned to Stuttgart and rejoined the no-longer outlawed Communist Party.
[2] However, with Cold War tensions rising rapidly as the Soviet Union consolidated its hold on central Europe, the military authorities were not willing to import a high-profile communist intellectual into Germany's US occupation zone, and when August Thalheimer died in September 1948 it was still as a German exile, still in Cuba.
[2] His widow, Bertha's sister in law Cläre, now left Cuba with her son: her destination was not Germany, however, but Australia, where she settled in Wandiligong and made a new life for herself as a teacher.
The group took its world political outlook largely from the writings of the format KPO policy man, Bertha's brother, August Thalheimer who was dying in Cuba during this time.
Within the trades union movement of the zones which became, after May 1949, the German Federal Republic (West Germany), the group promoted a robustly anti-Stalinist version of socialism.