His mother, Marie Pgetz, was a maid and his father, August Moser, was a house servant, who died young.

His family lived with his grandfather, an active member of the Social Democratic Party of Germany (SPD) until his mother remarried in 1917.

He then learned the trade of machine fitting on Hamburg wharfs and joined the metalworkers' union, where he was elected representative of the apprentices.

For a short time, he went to Kiel to help build a new anti-fascist organization to replace the RFB, which had been made illegal.

With Nazis in key positions in government, Adolf Hitler was able to push through the Reichstag Fire Decree, which was then signed into law by President Paul von Hindenburg.

He also began creating an archive for the group, which he conspired with a friend, Otto Gröllmann, who was a set designer at the Thalia Theater (Hamburg) to conceal there.

[1][5] After a wave of arrests began in Hamburg in October 1942, which included Bästlein and Abshagen, Jacob fled and went to Berlin, where he was again underground.

Bästlein was able to escape prison during a bombing raid in 1944 and ran into Jacob by chance, after which he joined them in forming the Saefkow-Jacob-Bästlein Organization,[3] also called the "Operative Leadership of the Communist Party in Germany".

In his publication, Am Beginn der letzten Phase des Krieges ("At the beginning of the last phase of the war"), Jacob wrote that to end the war and overthrow the fascist dictator, Communists should concentrate all their strength "on developing a broad, national front composed of all groups that stand opposed to fascism.

[7] Jacob lived underground in Berlin almost two years, moving frequently, some 30 times in 18 months,[7] and having to remain very quiet during the daytime, so as not to be overheard.

[citation needed] After Jacob was forced to flee to Berlin in October 1942, it was Charlotte Groß who brought him news of the birth of his daughter, Ilse, who was born on 9 November 1942.

[citation needed] Jacob's wife survived the war and became involved in the Union of Persecutees of the Nazi Regime.

[1] 55 million people in Germany and Europe were wiped out; gassed, fallen on the front lines, died where they lived.

I had to be able to face myself and my children.Historian and author Ursel Hochmuth (born 1931), daughter of Katharina and Franz Jacob's stepdaughter, has researched the German Resistance for decades and written several books on the subject.