There, he organized an illegal remembrance service for Edgar André and as a result was given another two years of imprisonment.
In 1944, he, Bernhard Bästlein and Franz Jacob led the Saefkow-Jacob-Bästlein Organization which agitated against the war in Berlin munitions plants, and called on people to commit sabotage.
It eventually took the form of the well-known 20 July bomb attack on the Führer at the latter's HQ, the Wolf's Lair in East Prussia.
Shortly before his death, he wrote to his wife Änne: "Through this letter I want to thank you, my comrade, for the greatness and beauty that you have given me in our life together... Not until today, writing these lines, thinking about you all, have my eyes moistened since the sentencing.
In Brandenburg an der Havel, the street running in front of the very prison where Saefkow and many other members of the antifascist resistance were executed has been named Anton-Saefkow-Allee.