Her elder brother, Paul, later died in the First World War: later still, in 1942, both her sisters, Wilhelmine and Bertha, would be deported to Auschwitz concentration camp and murdered.

[3] In 1908 a change in the law legalised female participation in politics,[5] and Wolfstein lost no time in joining the Social Democratic Party of Germany ("Sozialdemokratische Partei Deutschlands" / SPD).

[3] In 1910 she joined the National Employees Association ("Zentralverband der Angestellten" / ZdA), part of the Free Trade Union grouping.

One thing they had in common was a talent for public speaking, and the evening before the 1912 General Election – in which their SPD won twice as many votes as the next placed party – Luxemburg and Wolfstein, described by one admirer as a woman of small stature and extraordinary presence, shared a platform at the final major pre-election event.

In a secret police report dated 10 May 1917 Wolfstein was identified as a "fanatical individual" ("fanatische Persönlichkeit"): she and her fellow campaigners in Duisburg were frequently characterised as "enemy agents" ("feindliche Agenten").

In 1917 Wolfstein was at the founding conference of the breakaway faction, launched as the Independent Social Democratic Party ("Unabhängige Sozialdemokratische Partei Deutschlands" / USPD) at Gotha.

Unusually, in view of her gender, Wolfstein was elected to the Soldiers' and Workers' Council in Düsseldorf, which had become the focus of the revolution for the Lower Rhine region.

[2] Luxemburg was assassinated a couple of weeks later, but Wolfstein subsequently attended the Second World Congress of the Comintern, held in Moscow in July 1920.

[2] Together with her partner, Paul Frölich, for the next ten years she effectively worked as Luxemburg's literary executor, gathering together the various papers left behind into a coherent archive.

The KPDO itself split in 1932 and Rosi Wolfstein, together with Paul Frölich and political allies such as Jacob Walcher and August Enderle, joined with the left-wing breakaway faction that now formed the Socialist Workers' Party ("Sozialistische Arbeiterpartei Deutschlands" / SAPD).

Brandt is on record as commending Wolfstein's "commitment to a combative and liberal socialism" ("Engagement für einen kämpferischen und freiheitlichen Sozialismus").

In March 1933, Rosi Wolfstein, susceptible to Nazi persecution both because of her political record and on account of her Jewishness, fled to Brussels in Belgium.

[6] In Paris she was among the exiled socialists to sign the call, in December 1936, for a united Popular Front in order to "overthrow Hitler, and all who persecute the German people!

Nevertheless, she carefully observed the rising antisemitism and drew the consequences, which for her meant "supporting the socialist movement … because it wishes to abolish all differences.

Many of the camps used for "enemy aliens" had originally been set up to accommodate republican fighters returning from defeat in the Spanish Civil War, and initially the emphasis was not on security, but during 1941 the authorities began to formulate plans to separate out Jewish internees and ship them to equivalent facilities inside Germany where their circumstances would be more malign.

[1] She nevertheless remained firmly on the left of the party, an advocate, like her husband, of the elusive "third way" between Communism and Capitalism,[6] and convinced that for historical reasons only the SPD could deliver it.

[1] At her burial, which took place in the city's main cemetery, Holger Börner, the regional Minister-president, gave a speech of tribute, asserting that she "always fought with heart and mind for social causes" ("stets mit Herz und Verstand für die soziale Sache eingetreten") and celebrating her as "a second Rosa Luxemburg".