Urban was elected as its new president, defeating Paul Richter, the executive's preferred candidate.
He was then arrested, along with the ZdA's newspaper editor Georg Ucko, and charged with obscuring the union's balance sheets.
He spent several weeks in Plötzensee Prison, then lived quietly while maintaining links with the international trade union movement, personally visiting individuals in several countries.
[1] After World War II, Urban immediately joined the refounded SPD, and was a founding member of the Free German Trade Union Federation (FGDB).
He took part in the founding conference of the FGDB's Union of Commercial, Office and Administrative Workers, and argued for SPD and Communist Party of Germany (KPD) members to work together in unions, although he opposed a merger of the SPD and the KPD.